Spatio-temporal non-uniformity of urban park greenness and thermal characteristics in a semi-arid region

•Urban parks were non-uniform in remotely sensed greenness and surface temperature.•Negative correlation between greenness and temperature was stronger on warmer dates.•Park temperature increased with higher grass and lower woody cover and smaller area.•Temperature and greenness formed significant seasonally persistent local clusters.•Warmer parks were often smaller and located in warmer less green neighborhoods.