Climate change has become one of the most significant environmental challenges of the twenty-first century, altering temperature regimes and increasing the frequency and intensity of climate extremes. Due to its diverse topography and climatic conditions, Lorestan Province, western Iran, is highly vulnerable to these changes. This study aimed to evaluate the impacts of climate change on selected temperature extreme indices across Lorestan Province during the 2025–2055 period under the SSP2-4.5 scenario. Daily temperature data from 12 synoptic stations were used. Future climate projections were generated using the CanESM5 General Circulation Model (GCM) and statistically downscaled through the Statistical DownScaling Model (SDSM). Eight ETCCDI temperature extreme indices, including Diurnal Temperature Range (DTR), Cold Nights(TN10p), Warm Nights (TN90p), Cold Days (TX10p), Warm Days (TX90p), Summer Days (SU), Minimum of Daily Minimum Temperature (TNn), and Maximum of Daily Maximum Temperature (TXx), were calculated and analyzed.
The results indicate a pronounced warming trend across the province. Warm-related indices (TN90p, TX90p, and SU) showed significant increases, whereas cold-related indices (TN10p and TX10p) exhibited consistent declines. Moreover, TNn and TXx increased by approximately 2.17°C and 3.02°C, respectively, indicating weaker cold extremes and intensified heat extremes. In contrast, DTR decreased, suggesting that minimum temperatures are rising faster than maximum temperatures. Overall, the findings reveal a substantial shift in the regional thermal regime toward warmer conditions, characterized by more frequent and intense warm extremes and fewer cold events. These projected changes are expected to increase pressure on water resources, agriculture, ecosystems, and public health, emphasizing the urgent need to integrate climate change adaptation strategies into regional planning and sustainable resource management.