Climate exposures have been associated with cardiovascular health, but most studies focus on short-term exposure and individual climate parameters. This study explored the use of longitudinal multidimensional clustering in studying climate exposures over the life-course, in relation to adult blood pressure (BP). Annual averages of seven climate exposures were linked to the residential coordinates of the Northern Finland Birth Cohort 1966 (n = 4,225). Individual climate trajectories were grouped by a non-parametric algorithm for clustering joint trajectories (kml3d) across youth (4-24y) and adulthood (25-46y). Generalized linear models were used to assess the relationship between climate clusters and clinically measured systolic BP (SBP) and diastolic BP (DBP) at 46 years, adjusting for relevant confounders. Two youth clusters (A and B) were identified, while three clusters (A, B and C) emerged in adulthood. Compared to cluster A, the reference at both stages, B describes a colder northern climate, while C represents a transition to a warmer southern climate. Results show that growing up in the coldest climate (B) was associated with lower SBP (-1.13 mmHg, 95%CI -2.21, -0.05). Adult exposure to the warmest southern climate (C) was associated with lower SBP (-4.17 mmHg, 95%CI -5.38, -2.97) and DBP (-1.90 mmHg, 95%CI -2.72, -1.08). Youth and adult climate exposures were independently associated with adult BP. Future studies should assess to which extent health inequality plays a role. Our results show that kml3d clustering can identify distinct regional climates, facilitating observational studies on climate exposure.

Extreme heat is increasingly recognized as one of the most severe climate-related risks affecting urban populations, with disproportionate impacts on public health, energy systems, and vulnerable communities. As heatwaves intensify under climate change, cities require near-real time, high-resolution and actionable information to support early warning systems, preparedness, and long-term adaptation. Addressing this challenge at urban-local scale demands not only methodological innovation, but also robust digital infrastructures capable of delivering consistent and interoperable climate intelligence across regions.Destination Earth (DestinE), a strategic initiative of the European Union, represents a transformative step in this direction by providing global, high-resolution climate and weather simulations, through Digital Twins of the Earth System. By coupling advanced numerical models, Earth Observation (EO) data, and high-performance computing, DestinE establishes a common backbone for next-generation climate services. However, translating these powerful datasets into locally relevant, operational products for cities remains a critical challenge.DE_395-Urban Heat Health Forecasting (UHHF) project addresses this gap by demonstrating how DestinE Extremes Digital-Twin outputs can be transformed into urban-scale user-oriented heat-health indicators through the operational use of Machine Learning (ML). The project applies ML-based downscaling techniques to near-surface air temperature (T2m) and relative humidity (RH) forecasts, enhancing spatial resolution from kilometre-scale to approximately 200 m. These downscaled fields are subsequently used to derive human-biometeorological indicators such as the Universal Thermal Climate Index (UTCI) and Thermal Stress Duration (TSD), supporting health-oriented risk assessment.The UHHF framework integrates DestinE atmospheric drivers with EO-derived and geospatial predictors describing urban form, land cover, vegetation, and topography, including Local Climate Zones. Quality-controlled crowdsourced observations from citizen weather stations are combined with WMO reference data to constrain and validate the ML models, ensuring robustness under both average and extreme conditions. The approach is being implemented across four climatically and socio-environmentally diverse Functional Urban Areas, e.g. Naples, Chicago, Santiago, and Cape Town, enabling a systematic evaluation of models across continents.By building directly on DestinE and complementary European programmes led by ECMWF, ESA, and Copernicus, drawing on both their data assets and operational services, UHHF aims to illustrate how these can be leveraged to develop affordable, scalable, and reproducible urban-scale climate information and services. The project highlights the strategic importance of climate data platforms in bridging the gap between global simulations and local decision-making, contributing to the development of interoperable urban climate and health services aligned with European and international resilience frameworks.

Climate warming is driving more frequent and intense heat extremes. Yet, changes in heat stress, the leading cause of weather-related mortality, remain poorly quantified at the global scale. Here, using the Universal Thermal Climate Index, we assess heat stress globally since 1950, examining daytime extremes, nocturnal heat and compound daytime-nighttime events, revealing a pronounced, multidimensional intensification. Extreme 'feels-like' temperatures have become more frequent on every continent, and the spatial footprint of hazardous heat has expanded, exposing previously unaffected regions. Heat stress days and tropical nights have increased, with some regions experiencing up to 50 additional heat stress days annually and an extended heat stress season. The hottest nights of the year are warming faster (0.32 degrees C per decade) than the hottest days (0.27 degrees C), and compound events are more frequent, severe and prolonged. Population exposure to dangerous heat has increased markedly, driven by intensifying heat stress in addition to population growth.

As Europe warms at nearly twice the global average rate, extreme heat poses a growing public health threat. Effective, evidence-based communication on heat-related health is essential to reduce heat-related morbidity and mortality. Here we present an elicitation-based assessment of heat-related health communication strategies across Europe, drawing on expert consultations and an analysis of 11 campaigns implemented by national authorities in Germany, France, Greece and the Netherlands, as well as initiatives led by European-level institutions and global organizations such as the World Health Organization and World Meteorological Organization. Most initiatives reflect established health communication principles, but systematic pre-testing, behavioural evaluation and evaluation based on morbidity or mortality remain rare. Exceptions, such as France’s gain-framed, evaluation-driven campaign and the Netherlands’ current evaluation within the Dutch Heat Health Action Plan, show promising engagement and behavioural outcomes. We discuss substantial gaps in the evaluation and coordination of heat-related health messaging across Europe. To enhance public health preparedness and equity, we recommend data-driven, theory-informed communication design using behavioural models such as COM-B. A shared European database of validated materials and evaluation tools could support cross-country learning and evidence-based improvements. Strengthening pan-European collaboration might improve efficiency, consistency and impact while supporting equitable heat-related health protection as climate-related risks intensify.

Air temperature, humidity, wind, and cloudiness are influenced by sea and land breezes (SLB). They are also the main environmental determinants of human thermal comfort or lack thereof in coastal regions, leading to heat stress. This study evaluates, for the first time, the relief from or aggravation of heat stress in the context of SLB, and it does so by introducing a novel sea breeze identification method that combines meteorologically-based criteria with changes in a comfort-related index. Considering quality-controlled observations from a coastal station near Nice (France) in 31 summer seasons from 1993 to 2023, 590 sea breeze events are identified, which occur on 54% of summer days. The majority of the events (423) are associated with increases in humidity and wind speed and provide heat relief on their onset, which is mostly in the morning, by favouring the body's evaporative cooling, especially when air temperature decreases. In 167 events, heat aggravation is observed instead. Whether reducing or increasing air temperature, these events are characterised by increased humidity and weaker winds than the sea breezes in which relief occurs. The net result discourages the body's convective cooling mechanisms, favouring heat stress. Results confirm the relieving value of onshore over offshore winds, especially at the beginning of the summer season in June, unveiling the complexity of SLB in the thermal comfort domain and drawing attention to a more refined vision on heat in areas affected by local winds.Graphical AbstractGraphical abstract describing the data, methodology and results of a novel sea-land breeze identification method. Applied to quality-controlled observations made at a coastal station in Nice (France) for 31 summer seasons between 1993 and 2023 (left panel), the method merges meteorologically-based criteria with changes in a comfort-related index (Universal Thermal Climate Index) to assess the relief and aggravation of human heat stress caused by sea-land breezes (middle panel). Breezes are identified as heat-relieving events when they primarily occur in the morning and at the start of summer, whereas heat aggravation occurs with events characterised by increased humidity and weaker winds (right panel).

As the impacts of climate change on human health become increasingly evident, so does the need for a systemic and interdisciplinary understanding on the climate-health connection. Achieving such an understanding is key to the development of effective and rational adaptation plans, including those involving the creation of weather forecasts-driven systems that can increase the preparedness and response to health hazards. To address this shortcoming, the Horizon Europe project TRIGGER (SoluTions foR mItiGatinG climate-induced hEalth thReats) aims to generate and disseminate information about upcoming conditions detrimental to human health, such as heatwaves and cold spells, via an innovative prototype that integrates state-of-the-art climate and weather indicators with personal exposure monitoring data. We here present the TRIGGER prototype with a focus on the hydrometeorological prediction system that is tasked to forecasts health-impacting climate variables and indicators on temporal scales ranging from the short-range (hours) to sub-seasonal lead-time. Using a co-design approach involving medical doctors and epidemiologists, we describe how the system utilizes the ECMWF forecasts, provides probabilistic predictions for the near future, and enables the assessment of the associated uncertainty.

Heat-health warning systems and action plans, referred to as heat prevention plans (HPPs), are key public health interventions aimed at reducing heat-related mortality. Despite their importance, prior assessments of their effectiveness have yielded inconsistent results. The objective of this study is to systematically assess the effectiveness of HPPs in reducing heat-related mortality risk across Europe. We analysed daily mortality and mean temperature data from 102 locations in 14 European countries between 1990 and 2019. Using data from national experts, we identified the year of HPP implementation and categorised their development class. A three-stage analysis was conducted: (1) quasi-Poisson time series models were used to estimate location-specific warm-season exposure-response functions in 3 year subperiods; (2) mixed-effect meta-regression models with multilevel longitudinal structures were employed to quantify changes in pooled exposure-response functions due to HPP implementation, adjusted for long-term trends in heat-related mortality risks; and (3) the heat-related excess mortality due to HPP was calculated by comparing factual (with HPP) and counterfactual (without HPP) scenarios. Estimates are reported by country, region, and HPP class. HPP implementation was associated with a 25.2% [95% CI: 19.8% to 31.9%] reduction in excess deaths attributable to extreme heat, corresponding to 1.8 [95% CI: 1.3–2.4] avoided deaths annually per 100 000 inhabitants. This equates to an estimated 14 551 [95% CI: 10 118–19 072] total deaths avoided across all study locations following HPP implementation. No significant differences in HPP effectiveness were observed by European region or HPP class. Our findings provide robust evidence that HPPs substantially reduce heat-related mortality across Europe, accounting for temporal changes and geographical differences in risks. These results emphasise the importance of monitoring and evaluating HPPs to enhance adaptation to a warming climate.

Background: The complex interactions between heat and public health in tropical environments are not well understood, limiting the integrated understanding of heat-related impacts on the sustainability and resilience of the affected populations. Objectives: To provide evidence on the impact of heat stress on mortality in Puerto Rico by means of indices that are based on physiologically relevant environmental factors. Methods: Daily data on non-accidental mortality for the period of 2015-2020 were obtained from the Puerto Rico Department of Health. We obtained 2 meter ambient air temperature data across the whole geographical extent of Puerto Rico and for the 2015-2020 period at an hourly step from the ERA5 climate reanalysis dataset. We employed two indices derived from thermo-physiological models: the Universal Thermal Climate Index (UTCI) and the Heat Index (HI). Poisson regression models were fitted to explain the total number of deaths as a function of UTCI and HI while adjusting for sex and age. Results: We observed an increase in overall non-accidental mortality in the days categorized as the highest tertile of both HI (IRR: 1.23, 95% CI: 1.21; 1.25) and UTCI (IRR:1.47, 95% CI: 1.44; 1.49) in the adjusted model. Myocardial infarction, ischemic heart disease, heart failure, and cerebrovascular disease were some of the primary causes of death. Conclusion: Results will provide local decision-makers with sufficient evidence on heat stress impacts and valuable information on vulnerability that can be translated into heat adaptation strategies in Puerto Rico.

This study focuses on local climate modifications as observed in historical records of climate normals and in reanalysis-derived thermal stress data for two years unaffected by El Niño (1985 and 2020) across an approximately southeast-northwest transect over the Brazilian territory. Six major cities were analyzed, namely Porto Alegre, Curitiba, Brasília, Cuiabá, Porto Velho, and Manaus, each characterized by distinct climatic conditions. Climate normals were obtained from the network of the Brazilian Institute of Meteorology (INMET) whereas heat stress data represented by the Universal Thermal Climate Index (UTCI) were retrieved from the ERA5-HEAT reanalysis dataset. Urbanization was interpreted as changes in impervious surfaces observed from satellite imagery, which allowed us to identify the growth and spread of the impervious area in the cities. A consistent but not uniform rise in temperature and heat stress was found in the evaluated locations, with a more pronounced rise in heat stress in low-latitude locations. Among temperature- and thermal stress-related variables, the increase in impervious surfaces appears to correlate more strongly to a rise in maximum temperatures and in the average UTCI, with statistically significant impact on changes in the ‘moderate heat stress’ class of the UTCI. The consideration of the breakdown of degrees of imperviousness over urban areas has been found to be more defining of changes in local climate conditions than the bulk change in impervious surfaces over time.

Extreme temperatures, such as those experienced during a heatwave, represent a dangerous meteorological hazard to human health. Heat disorders such as heat exhaustion and sunstroke are harmful to people of all ages and responsible for excess morbidity and mortality in affected areas. This chapter introduces the ANYWHERE system as the first implementation of a real-time decision support platform for two weather-induced health hazards: heatwaves and air quality. The system is based on state-of-the-art forecasting algorithms that deliver eight 24/7 heatwave and air quality products generated by a common numerical weather prediction model, i.e. the integrated forecasting system from the European Centre for Medium-Range Weather Forecasts (IFS-ECMWF). The chapter provides a detailed description of the ANYWHERE heatwave and air quality products, and their implementation in seven pilot sites. It concludes with a discussion on future developments and applications for ANYWHERE heatwave and air quality products.

Farmworkers, the ‘frontline workers’ of our food system, are often exposed to heat stress that is likely to increase in frequency and severity due to climate change. Irrigation can exacerbate heat stress, quantification of which is crucial in intensely irrigated agricultural lands such as the Imperial Valley (IV) in southern California. We present high-resolution maps of wet bulb globe temperature (WBGT), a key indicator of heat exposure in humans, over the IV and quantify the impact of irrigation during day and night in agricultural and urban settings. We derive WBGT from a high-resolution regional climate model (WRF), which shows robust performance against station-derived WBGT metrics yielding R-square up to 0.95 and RMSE as low as 0.71 ℃ in agricultural sites. We find that irrigation reduces WBGT by 0.3-1.3 ℃ during the wet season in the daytime due to strong evaporative cooling. However, during dry season, irrigation increases WBGT by 0.4-1.3 ℃ at night, when the large increase in humidity sufficiently raises the wet-bulb temperature (WBT) with added increase in dry-bulb temperature (DBT) and black globe temperature (BGT), surpassing the weaker evaporative cooling. We also find that the urban and fallow areas adjacent to the crop fields experience increased heat stress due to moisture advection. Modeled WBGT frequently exceeds the regulatory threshold of 24.4 ℃ in the crop fields during key harvest seasons with exceedances greater than 50, 150, and 300 hours in April, June, and August 2020, respectively. The heat stress modeling framework presented serves as a prototype to develop climate change adaptation strategies for the agricultural regions of the Imperial Valley as well as the broader Central Valley and inform labor and environmental policies in California and elsewhere.

Farmworkers, the frontline workers of our food system, are often exposed to heat stress that is likely to increase in frequency and severity due to climate change. Irrigation can either alleviate or exacerbate heat stress, quantification of which is crucial in intensely irrigated agricultural lands such as the Imperial Valley in southern California. We investigate the impact of irrigation on wet bulb globe temperature (WBGT), a key indicator of heat exposure in humans, using a validated high-resolution Weather Research and Forecasting (WRF) regional climate model, during day and night and in different seasons. We find that irrigation reduces WBGT by 0.3-1.3 degrees C during the daytime in summer due to strong evaporative cooling. However, during the summer nights, irrigation increases WBGT by 0.4-1.3 degrees C, when a large increase in humidity sufficiently raises the wet-bulb temperature. Urban and fallow areas adjacent to cropped fields also experience increased heat stress due to moisture advection from irrigated areas. Our results can inform heat-related policies in agricultural regions of California and elsewhere.

Weather and climate patterns play an intrinsic role in societal health, yet a comprehensive synthesis of specific hazard-mortality causes does not currently exist. Country-level health burdens are thus highly uncertain, but harnessing collective expert knowledge can reduce this uncertainty, and help assess diverse mortality causes beyond what is explicitly quantified. Here, surveying 30 experts, we provide the first structured expert judgement of how weather and climate directly impact mortality, using the UK as an example. Current weather-related mortality is dominated by short-term exposure to hot and cold temperatures leading to cardiovascular and respiratory failure. We find additional underappreciated health outcomes, especially related to long-exposure hazards, including heat-related renal disease, cold-related musculoskeletal health, and infectious diseases from compound hazards. We show potential future worsening of cause-specific mortality, including mental health from flooding or heat, and changes in infectious diseases. Ultimately, this work could serve to develop an expert-based understanding of the climate-related health burden in other countries.

The Wet Bulb Globe Temperature (WBGT) is an international standard heat index used by the health, industrial, sports, and climate sectors to assess thermal comfort during heat extremes. Observations of its components, the globe and the wet bulb temperature (WBT), are however sparse. Therefore WBGT is difficult to derive, making it common to rely on approximations, such as the ones developed by Liljegren et al. (2008, https://doi.org/10.1080/15459620802310770, WBGTLiljegren ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{L}\mathrm{i}\mathrm{l}\mathrm{j}\mathrm{e}\mathrm{g}\mathrm{r}\mathrm{e}\mathrm{n}}$ ) and by the American College of Sports Medicine ( WBGTACSM87 ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{A}\mathrm{C}\mathrm{S}\mathrm{M}87}$ ). In this study, a global data set is created by implementing an updated WBGT method using ECMWF ERA5 gridded meteorological variables and is evaluated against existing WBGT methods. The new method, WBGTBrimicombe ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{B}\mathrm{r}\mathrm{i}\mathrm{m}\mathrm{i}\mathrm{c}\mathrm{o}\mathrm{m}\mathrm{b}\mathrm{e}}$ , uses globe temperature calculated using mean radiant temperature and is found to be accurate in comparison to WBGTLiljegren ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{L}\mathrm{i}\mathrm{l}\mathrm{j}\mathrm{e}\mathrm{g}\mathrm{r}\mathrm{e}\mathrm{n}}$ across three heatwave case studies. In addition, it is found that WBGTACSM87 ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{A}\mathrm{C}\mathrm{S}\mathrm{M}87}$ is not an adequate approximation of WBGT. Our new method is a candidate for a global forecasting early warning system.

As the linkages between extreme weather events, changes in climatic conditions and health impacts in exposed populations become clearer, so does the need for climate‐smart decisions aimed at making the public health sector more responsive and resilient. By integrating climate and health information, climate services for health provide robust decision‐support tools. The Lancet Countdown monitoring system uses global climate reanalyses products to track annual changes in a set of health‐related outcomes. In the monitoring system, multiple variables from reanalysis datasets such as ERA5 and ERA5‐Land are retrieved and processed to capture heatwaves, precipitation extremes, wildfires, droughts, warming and ecosystem changes across the globe and over multiple decades. This reanalysis‐derived information is then input into a hazard–exposure–vulnerability framework that delivers, as outcomes, indicators tracking the year‐by‐year impacts of climate‐related hazards on human mortality, labour capacity, physical activity, sentiment, infectious disease transmission, and food security and undernutrition. Building on the reanalysis gridded format, the indicators create worldwide ‘maps without gaps’ of climate–health linkages. Our experience shows that reanalysis datasets allow standardization across the climate information used in the framework, making the system potentially adaptable to multiple geographical scales. An ongoing challenge is to quantify how the inherent bias of global reanalyses influences indicator outcomes. We foresee the health sector as a key user of reanalysis products. Therefore, public health professionals and health impact modellers should be involved in the co‐development of future iterations of reanalysis datasets, to reach finer spatial resolutions and provide a wider set of health‐relevant climate variables.

The Lancet Countdown is an international research collaboration that independently monitors the evolving impacts of climate change on health, and the emerging health opportunities of climate action. In its eighth iteration, this 2023 report draws on the expertise of 114 scientists and health practitioners from 52 research institutions and UN agencies worldwide to provide its most comprehensive assessment yet.

A current systematic literature review has stated several deficiencies and knowledge gaps in biometeorology research conducted in Brazil. This finding encouraged a group of local professionals in the field to foster research initiatives in topics and regions yet unexplored in the country. Motivated by that, the group organized the first Brazilian Symposium on Human Biometeorology between July 4 and 8, 2022, in Natal (RN), northeastern Brazil. This paper aims to summarize the main studies presented at the symposium and highlight a few ideas that could be pursued next in human biometeorology in future research initiatives.

Background In the past decades, climate change has been impacting human lives and health via extreme weather and climate events and alterations in labour capacity, food security, and the prevalence and geographical distribution of infectious diseases across the globe. Climate change and health indicators (CCHIs) are workable tools designed to capture the complex set of interdependent interactions through which climate change is affecting human health. Since 2015, a novel sub-set of CCHIs, focusing on climate change impacts, exposures, and vulnerability indicators (CCIEVIs) has been developed, refined, and integrated by Working Group 1 of the “ Lancet Countdown: Tracking Progress on Health and Climate Change”, an international collaboration across disciplines that include climate, geography, epidemiology, occupation health, and economics. Discussion This research in practice article is a reflective narrative documenting how we have developed CCIEVIs as a discrete set of quantifiable indicators that are updated annually to provide the most recent picture of climate change’s impacts on human health. In our experience, the main challenge was to define globally relevant indicators that also have local relevance and as such can support decision making across multiple spatial scales. We found a hazard, exposure, and vulnerability framework to be effective in this regard. We here describe how we used such a framework to define CCIEVIs based on both data availability and the indicators’ relevance to climate change and human health. We also report on how CCIEVIs have been improved and added to, detailing the underlying data and methods, and in doing so provide the defining quality criteria for Lancet Countdown CCIEVIs. Conclusions Our experience shows that CCIEVIs can effectively contribute to a world-wide monitoring system that aims to track, communicate, and harness evidence on climate-induced health impacts towards effective intervention strategies. An ongoing challenge is how to improve CCIEVIs so that the description of the linkages between climate change and human health can become more and more comprehensive.

Forty years (1980-2019) of reanalysis data were used to investigate climatology and trends of heat stress in the Caribbean region. Represented via the Universal Thermal Climate Index (UTCI), a multivariate thermophysiological-relevant parameter, the highest heat stress is found to be most frequent and geographically widespread during the rainy season (August, September, and October). UTCI trends indicate an increase of more than 0.2°C·decade-1, with southern Florida and the Lesser Antilles witnessing the greatest upward rates (0.45°C·decade-1). Correlations with climate variables known to induce heat stress reveal that the increase in heat stress is driven by increases in air temperature and radiation, and decreases in wind speed. Conditions of heat danger, as depicted by the heat index (HI), have intensified since 1980 (+1.2°C) and are found to occur simultaneously to conditions of heat stress suggesting a synergy between heat illnesses and physiological responses to heat. This work also includes the analysis of the record-breaking 2020 heat season during which the UTCI and HI achieved above average values, indicating that local populations most likely experienced heat stress and danger higher than the ones they are used to. These findings confirm the gradual intensification of heat stress in the Caribbean and aim to provide a guidance for heat-related policies in the region.

The 2022 report of the Lancet Countdown is published as the world confronts profound and concurrent systemic shocks. Countries and health systems continue to contend with the health, social, and economic impacts of the COVID-19 pandemic, while Russia's invasion of Ukraine and a persistent fossil fuel overdependence has pushed the world into global energy and cost-of-living crises. As these crises unfold, climate change escalates unabated. Its worsening impacts are increasingly affecting the foundations of human health and wellbeing, exacerbating the vulnerability of the world's populations to concurrent health threats.