Ethiopia’s large land area and diverse topography results in different climates across the country as well as temperature and precipitation disparity across its regions. Ethiopia’s equatorial rainforests in the south and southwest are characterized by high rainfall and humidity, while the Afro-Alpine on the summits of the Semien and Bale mountains, and the north-east, east and south-east lowlands experiencing desert-like conditions. The highland regions in the center and north of the country experience cooler climates. The eastern corner of the country is very arid and experiences very little rainfall. Seasonal rainfall in Ethiopia is driven mainly by the migration of the Inter-Tropical Convergence Zone (ITCZ) and there is strong inter-annual variability of rainfall across the country. Ethiopia has three rainfall seasons: Bega, Belg, and Kiremt. The primary rainy season, Kiremt, occurs from mid-June to mid-September and accounts for 50–80% of annual rainfall. Parts of central and northern Ethiopia experience a sporadic, secondary wet-season, Belg, which often has considerably less rainfall and occurs from February to May. Southern regions of Ethiopia experience two distinct wet seasons, Belg, from February to May, and Bega occurring from October to December, which has drier and colder conditions. Mean annual rainfall distribution is approximately 2,000 mm over the south-western highlands and less than 300 mm over the south-eastern and north-eastern lowlands. Temperatures across Ethiopia can range from –15°C over the highlands, to above 25°C in the lowlands.
- Average temperatures in Ethiopia have increased by an average of 1°C since 1960, at an average rate of 0.25°C per decade.
- Increases have been most noticeable from July through September.
- The average number of ‘hot nights’ (the hottest 10% of nights annually) increased by 37.5% between 1960 and 2003 and the average number of ‘hot days’ per year, increased by 20%; cold days have also decreased.
- Observed temperature increases have also led to increased evapotranspiration and reduced soil moisture; higher rates of warming have been observed in the central regions and highland areas.
- Strong variability makes long-term precipitation trends for Ethiopia difficult to determine, however an overall decline has been observed in the last three to four decades, with significant year-to-year volatility.
- Some areas of the country are expected to experience a reduction in rainfall. For example, the south-central region of the country has experienced a 20% decrease in rainfall since 1960.
- While high degrees of inter-annual variability exist for precipitation trends across Ethiopia, the incidence of drought increased and the rains in central and northern areas occurring in February to May have become increasingly less predictable.
- The rise of sea surface temperatures in the Indian Ocean influences the migration of the ITCZ which can further increase variability in the timing and duration of rainfall seasons, altering traditional rainfall patterns and causing more frequent drought.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.