Spatio-temporal trends in extreme climatic variables: a focus in southern Ethiopia

Abstract Climate change threatens Ethiopian smallholder farmers, where agriculture heavily reliant on rainfall, is increasingly at risk due to these changes. The main objective of the study to analyze the spatio-temporal trends of extreme climatic variables in the Wolaita zone of southern Ethiopia. Accordingly, this study seeks to answer the following research question: What are the spatio-temporal trends of extreme rainfall and temperature variables in the Wolaita zone? R software was used to assess extreme rainfall and temperature indices. The Modified Mann–Kendall test and Sen’s slope estimators were employed to identify trends in temperature and rainfall extremes using data from 1990 to 2023. Results showed no significant trend in the annual total rainfall from wet days. The highest monthly rainfall, averaging 155.057 mm, occurred between April and August, while the lowest levels were observed in January, February, March, and December. In contrast, temperature indices indicated a warming trend, with annual warm days (TX90p) and warm nights (TN90p) values increasing by 0.649–5.00 °C and 0.09–4.22 °C, respectively. The maximum warm night temperature (TNx) ranged from 16.49 to 17.95 °C, while the maximum daily temperature (TXx) varied from 29.25 to 32.20 °C across different agroecological zones, showing an upward trend at seven stations. Decreasing trends were noted for TN10p and TX10p.These trends in extreme rainfall and rising temperatures may impact agriculture, water resources, and health, emphasizing the urgent need for adaptation strategies. Implementing measures such as soil–water conservation and crop diversification is crucial to address rainfall variability and rising temperatures.