Evidence of Warming and Rainfall Variability in a Highland Region of Ethiopia: Climate Extremes in Jama District (1981 to 2020)

This research assesses long-term trends in Jama District, South Wollo Zone, Ethiopia, of temperature and precipitation extremes using daily meteorological data (1981-2020) from Ethiopian Meteorology Institute (EMI). A total of 22 climate extreme indices—12 are for temperature and 10 are for precipitation—were computed following Expert Team on Climate Change Detection and Indices (ETCCDI) recommendations. The non-parametric Mann-Kendall test and Sen's slope estimator were applied to identify trends. Results show a statistically significant warming trend for several indices: rising hot days (SU25) by 3.936 days/year (p < 0.001), warm nights (TN90p) by 0.538 days/year (p = 0.001), and warm days (TX90p) by 0.597 days/year (p = 0.008). In contrast, cool nights (TN10p), cool days (TX10p), and cold spell duration (CSDI) decreased significantly by −0.541, −0.384, and −0.098 days/year, respectively (all p < 0.05), indicative of a sharp shift towards heat extremes. Precipitation indices were in overall positive but statistically not significant trends. Wet-day precipitation throughout the year (PRCPTOT) rose by 2.999 mm/year (p = 0.224), while heavy rainfall days (R10 and R20) rose by 0.170 and 0.076 days/year, respectively. Rainfall intensity (SDII) rose slightly by 0.027 mm/day/year. Extreme rainfall amounts (RX1day, RX5day) and wet/dry spell lengths (CWD, CDD) saw no changes. These findings confirm a clear warming signal and moderate rainfall variability, with important implications for agriculture, water resources, and climate adaptation planning in this vulnerable highland region.