Ethiopia sees sustained rise in heatwave frequency, duration and intensity

The research, published in Discover Atmosphere, analysed quality-controlled daily maximum and minimum temperatures from 1991 to 2025 and found that warm extremes have risen sharply while cold extremes have declined across all major regions of the country.

The study, led by Tofikk Redi, relied entirely on ground-based observations from the Ethiopian Meteorological Institute rather than simulated or projected climate data. Daily maximum temperature (Tmax) and minimum temperature (Tmin) records were subjected to rigorous quality control, including screening for outliers, physically implausible values and internal inconsistencies such as daily minimum temperatures exceeding daily maxima. Stations with more than 25 percent missing observations over the study period were excluded, and short gaps of up to three consecutive days were filled using linear temporal interpolation, while longer gaps were reconstructed from neighbouring stations through inverse distance weighting where applicable.

To ensure the reliability of the long-term records, the researchers applied homogeneity testing using the Standard Normal Homogeneity Test, the Pettitt test and the Buishand range test to detect breakpoints caused by non-climatic factors such as station relocation, instrumentation changes or environmental modification. Significant inhomogeneities were corrected using relative homogenization techniques based on reference station series, and only homogeneous or properly adjusted datasets were retained for the heatwave analysis.

Temperature extreme indices and heatwave metrics were computed using the internationally recognized ETCCDI framework, with percentile thresholds calculated against a 1991–2020 climatological baseline in line with World Meteorological Organization guidelines for 30-year reference periods. Heatwaves were defined as periods of at least five consecutive days during which daily maximum temperature exceeded the baseline 90th percentile. From this definition the team derived heatwave frequency, the number of events within a given period; heatwave duration, the average length of events in days; and separate intensity measures for daytime and nighttime temperatures, calculated as the mean exceedance above the respective 90th percentile thresholds during heatwave days. Compound heatwave conditions, in which both daytime and nighttime thresholds were exceeded simultaneously, were also identified to capture combined thermal stress.

The results show a consistent warming trend across Ethiopia, with both Tmax and Tmin exhibiting persistent increases over the study period. The decadal analysis reveals a striking progression: in the first decade, from 1991 to 2000, Tmax and Tmin showed mainly negative or weak trends, indicating slight cooling across much of the country. The second decade, 2001 to 2010, acted as a transition, during which some regions continued to cool while significant warming emerged in western, central and southeastern Ethiopia. By the third decade, 2011 to 2020, the warming signal dominated most of the country, with increases surpassing 1 degree Celsius per decade for both Tmax and Tmin extending over extensive areas, a pattern the authors describe as a strong acceleration of the warming rate.

Warm extremes showed a significant upward shift throughout the record, with the percentage of warm days (TX90p) and warm nights (TN90p) rising, while cold days (TX10p) and cold nights (TN10p) declined markedly across all major regions. During the baseline period, heatwave frequency values were highest in the eastern and southeastern lowlands, ranging from 66 to 100 percent, indicating persistent exposure to warm extremes. Duration values ranged from 15 to 66 percent for prolonged events concentrated in eastern and southeastern Ethiopia, while intensity peaked in the southern and southwestern regions at roughly 49 to 83 percent. Cold extremes, by contrast, showed generally lower frequency, shorter duration and weaker intensity, confirming the dominance of warming-related extremes across the country during the baseline period.

For the recent period from 2021 to 2025, evaluated against the 1991–2020 baseline, the analysis found that warming has continued but become more localized and intensified. Tmax showed particularly strong warming in central Ethiopia, especially in and around Addis Ababa and the adjacent highlands, while Tmin increased relatively weakly with a more spatially homogeneous pattern. The authors caution that the short five-year window makes these recent trends more susceptible to interannual variability, and they note that northern areas showed a slight cooling signal in some warm-night indices that is likely related to short-term variability rather than a reversal of the long-term pattern.

The nighttime picture is particularly notable. Compared with the baseline, the 2021–2025 maps indicate a marked increase in warm-night occurrences and combined nighttime thermal extremes across most of Ethiopia, with the strongest intensification observed over the central, northern, northwestern and southwestern regions. The authors interpret this pattern as reduced nocturnal cooling and greater heat retention, which they describe as a well-documented signal of regional warming. Southern and western Ethiopia showed widespread expansion of warm-night frequencies, while northeastern and southeastern areas also exhibited elevated warm-night conditions, albeit with relatively lower intensity than the central highlands and western regions.

Daytime extremes tell a similar story. The 2021–2025 records reveal a substantial increase in warm-day and combined daytime extreme temperature events relative to the baseline climatology, with the highest concentrations of warm-day frequencies in the central, northern and northwestern regions. Southwestern and western Ethiopia also showed notable expansion of extreme daytime temperatures, and northeastern and southeastern areas displayed moderate but spatially widespread increases, suggesting the extension of heat stress into arid and semi-arid zones. Warm-day intensity reached 66 to 100 percent in southeastern and central highland zones during the recent period, while heatwave duration remained relatively low nationwide, mostly between 15 and 32 percent, indicating short-lived events despite their recurrence.

The authors are careful to frame their findings appropriately, noting that the results do not indicate statistical robustness in a methodological sense but rather demonstrate a consistent directional warming pattern supported by decadal and spatial trends derived from standardized indices. They emphasize that variations in heatwave metrics during the short 2021–2025 window should be interpreted cautiously due to the limited temporal span and strong interannual climate variability. Nevertheless, they conclude that Ethiopia is experiencing a clear and sustained shift toward more frequent and intense heatwave conditions, with increasing exposure carrying important implications for agriculture, public health, water resources and urban systems. The findings point to the need for region-specific adaptation strategies, including heatwave early warning systems that account for both daytime and nighttime extremes, climate-resilient agricultural planning, integration of heatwave indicators into watershed and reservoir management, expansion of urban green spaces, and the strengthening of meteorological monitoring in the southeastern lowlands and transitional highland–lowland zones where data gaps may limit early detection of extreme heat.

Subject of Research: Spatiotemporal trends in temperature extremes and heatwave characteristics across Ethiopia from 1991 to 2025

Article Title: Implications of heatwave dynamics for adaptation and resilience in Ethiopia

Article References: Redi, T. (2026). Implications of heatwave dynamics for adaptation and resilience in Ethiopia. Discover Atmosphere, 4(1), Article 28. https://doi.org/10.1007/s44292-026-00093-7

Image Credits: AI Generated

DOI: 10.1007/s44292-026-00093-7

Keywords: Ethiopia, heatwaves, temperature extremes, climate change, ETCCDI indices, warm nights, East Africa, adaptation, meteorological stations, climate risk, Tmax, Tmin