Ethiopia Fact

The climatic map drawn according to the Koppen System, shows the various climatic regions of Ethiopia.

This system is based on the annual and monthly means of temperature and rainfall also on seasonal changes of rainfall and types of native vegetation associated with them.

The climatic types range from equatorial desert to hot and cool steppe, and from tropical savannah and rain forest to warm temperate and cool highland.

It is also broadly divided into highland and lowland regions with elevations ranging from around 110 metres below sea level in the Dallol Depression and rising to 4,620 metres in Ras Dejen in the Simen Mountain Massif.

Climate ranges not only from arid areas to areas of rather plentiful moisture, but also from hot lowland to cool highlands.

The climate is grouped into three types;
I. Dry climate
II. Tropical rainy climate
III. Temperate rainy climate

These three main climatic regions are each subdivided into three or more types, making a total of nine principal climatic types, as follows:

1. BWH – hot arid climate:- Barren to sparse vegetation. In this region the mean annual temperature is between 270C and 300C; and mean annual rainfall is less than 450mm.

It is usually characterized by strong wind, high temperature, low relative humidity and little cloud. Evaporation is twenty or more times in excess of rainfall in some places.

2. BSH – hot semi-arid climate:- Steppe type vegetation. In this region the mean annual temperature is between 180C and 270C; and mean annual rainfall is 410-820mm.

The rainfall is highly variable from year to year. Since evaporation exceeds rainfall, permanent streams do not originate.

Grasses are less tall and coarse and edible, but during the dry seasons they are not very palatable, so that wild game and cattle at such times rely largely on the tender fresh grasses along water courses. This region is intermediate between the arid desert and the humid climate.

3. BSK – cool semi-arid climate:- Steppe type vegetation mainly over the adjacent highlands of Tigray. The mean annual temperature is 120C to 180C; and mean annual rainfall is between 400 and 620mm. Evaporation is less than BSH, due to the low temperature of this region and therefore it is less arid than BSH.

4. AS – tropical climate I: This region has dry months in summer. The mean temperature of the coldest month is above 180C and mean annual rainfall is between 680 and 2,000mm. This region is found in a very small area between Asmera and Mitsiwa.

5. AW – tropical climate II:- This climate prevails up to an elevation of 1,750 metres above mean sea level. The lengths of the wet and dry periods vary considerably from the western part to the northern and eastern parts of the country. Tall grass characterizes this climate type. Usually grass and trees are intermingled.

6. AM – tropical climate III:- It is known as tropical rainforest climate. Temperature of the coldest month is above 180C and mean annual rainfall is between 1,200 and 2,800mm.

It differs from AW climate by the total amount that falls during the driest month. It supports an evergreen rainforest. It prevails up to elevations of 1,750 metres above mean sea level.

7. CWB – warm temperature climate I:- This has distinct dry months in winter. The mean temperature of the coldest month is below 180C, and for more than four months it has mean temperatures above 100C.

The annual rainfall in mm is also greater than twenty times the annual mean temperature plus fourteen [20 (t+14)].

Rainfall distribution and amount varies considerably from area to area. In areas of heavy rainfall, forests predominate and grass covers the areas of moderate rainfall. It prevails from an elevation of 1,750 metres to 3,200 metres above sea level.

8. CFB – warm temperate climate II:- This has more soil moisture than CWB climate. It is a humid temperate climate without dry season and mean temperature of the coldest month is less than 180C.

Rainfall of the driest summer month is greater than one-third of the wettest winter month, and rainfall of the driest winter month is also greater than one-tenth of the wettest summer month.

The area experiences adequate rainfall at all seasons. This climate is suitable for abundant forest cover.

9. CWC – cool highland climate:- This is characterized by dry months in winter and 100C or less of mean temperature of the warmest month; the annual rainfall is between 800 and 2000m.

This area is situated at an altitude equal to, or more than 3,500 metres above mean sea level. It is found on small isolated high areas.

(Source: National Atlas of Ethiopia)

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