The Greater Horn of Africa (GHA) is expected to experience intense weather activity during the week of 17 to 24 September 2025, with forecasts indicating heavy rainfall and elevated heat stress across several countries.
Heavy rainfall is likely over central to south-eastern Sudan, western Eritrea, northern to eastern Ethiopia, and north-eastern Somalia. In particular, isolated areas in central and northern Ethiopia, as well as south-eastern Sudan, could receive more than 200 mm of rainfall over the week.
Moderate rainfall, ranging between 50 and 200 mm, is forecast across a broad swath of the region, including most parts of Uganda, South Sudan, southern Sudan, central, western, and northern Ethiopia, western Eritrea, north-eastern Somalia, and much of the Lake Victoria Basin in Kenya, as well as Rwanda and Burundi.
Meanwhile, light rainfall, below 50 mm, is anticipated in central to northern Sudan, southern Eritrea, Djibouti, south-eastern Ethiopia, southern Kenya, and most of Somalia and Tanzania. As a reminder, 1 mm of rainfall equals 1 litre of water per square meter, meaning even light rains can be significant over wide areas.
GHA Rainfall Anomalies
Several regions in the Greater Horn of Africa (GHA) are likely to receive more rainfall than usual, including most of South Sudan, central and southern Sudan, northern and eastern Uganda, central to western Kenya, central and northern Ethiopia, Eritrea, Djibouti, northern Somalia, Rwanda, Burundi, and north-western Tanzania.
In contrast, less-than-usual rainfall is expected in western South Sudan, central and south-eastern Ethiopia, central Somalia, and western Uganda.
Forecasts show that rainfall may exceed the 90th percentile, among the highest levels on record, in areas of central to south-eastern Sudan, western Eritrea, northern and eastern Ethiopia, and north-eastern Somalia.
These intense conditions raise the risk of localized flooding, particularly in flood-prone zones of central-eastern Sudan and northern to north-eastern Ethiopia.
GHA East Africa Temperature Conditions
The region will continue to experience high temperatures, especially in central to northern Sudan and the Afar region of Ethiopia, where temperatures are expected to rise above 32°C.
Elsewhere, moderate to high temperatures, ranging from 20°C to 32°C, are expected across Sudan, South Sudan, Eritrea, Djibouti, Somalia, south-eastern Ethiopia, eastern and northern Kenya, eastern Rwanda and Burundi, and most of Tanzania.
Mild conditions, with temperatures below 20°C, are forecast in central Ethiopia, central to south-western Kenya, western Rwanda and Burundi, and parts of central Tanzania.
Temperature Anomalies and Heat Stress
Warmer-than-usual temperatures are expected to persist over most parts of the Greater Horn of Africa, although cooler-than-average conditions may occur in eastern South Sudan, south-eastern Sudan, and western Eritrea.
At the same time, elevated levels of heat stress are anticipated in most parts of Sudan, along the Red Sea coast, and within the Afar region of Ethiopia. These conditions could impact human health, livestock, and water resources, especially in already vulnerable communities.
