Urticaceae pollen is among the most abundant herbaceous pollen types in Central Europe and contributes to seasonal allergic symptoms. This study analysed the spatiotemporal variability, long-term trends, and predictability of Urticaceae pollen at eight urban sites in Slovakia and the Czech Republic, using aerobiological records of 14–32 years. Main pollen season timing, duration, and intensity were related to meteorological variables, and statistical models were developed to predict exceedances of ≥80 pollen/m3, used as an aerobiological benchmark for high-concentration days. Warmer lowland sites showed earlier and longer pollen seasons than cooler sites. Trend analyses revealed site-specific changes, but only the earlier season onset in Liberec and Prague and the longer season in Prague remained significant after false discovery rate correction. These changes were partly associated with spring temperatures and precipitation. Seasonal pollen intensity showed heterogeneous trends, and longer seasons were not necessarily accompanied by a higher seasonal pollen integral. Mean F1 scores of the predictive models ranged from 58% to 76% at four sites (Banská Bystrica, Košice, Prague, and Bratislava) and from 19% to 53% elsewhere; all models outperformed a trivial prevalence-based reference classifier. Temperature, sunshine duration, and precipitation were predominantly positively associated with exceedance probability, with positive precipitation effects confined to lags of 6–13 days, whereas wind speed and relative humidity showed variable effects. The results indicate that climate and local environmental conditions jointly shape Urticaceae pollen dynamics and highlight both the potential of statistical approaches for forecasting high-concentration days and the importance of site-specific factors.
