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Above-average rainfall received across most of the region in March, alleviating dryness but also causing flooding

  • Seasonal Monitor
  • East Africa
  • March 31, 2023
Above-average rainfall received across most of the region in March, alleviating dryness but also causing flooding

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  • Key Messages
  • Seasonal Progress
  • Forecast
  • Partner
    Key Messages
    • The onset of the March – May rainy season was mixed across the region. Most areas experienced the start of the seasonal rains in early- to late-March, with abnormally heavy to very heavy episodic rainfall (more than 200 percent of average amounts) over the western and northern sectors of the region. Meanwhile, the rains are yet to be fully established over coastal regions of Kenya and Tanzania, with evidence of significant early season deficits (less than 60 percent of average amounts), attributed to persistent impacts of tropical cyclone Freddy, which diverted moisture and rainfall to southern Africa.

    • The recent rains have had beneficial impacts on rangeland resources (pasture and water resources) and have facilitated planting activities in zones with medium to high potential for cereal crops. However, the episodic heavy rains have reportedly led to flash floods due to high water runoff in extremely dry and hardened land following the prolonged severe drought conditions since 2020. These flash floods caused serious property damage and loss of livestock in several cities and pastoral regions of eastern Ethiopia and northern and western Kenya.

    • Available forecasts for April indicate the full establishment of seasonal rains and an increased likelihood of wetter-than-average conditions across equatorial East Africa at the peak of the seasonal rains in April. However, there are also indications of likely persistent below-average rainfall performance over portions of East Africa’s coastal strip and parts of the western sector during this month. Land surface temperature are forecast to be generally near average across the region.

    Seasonal Progress

    Early to timely onset of seasonal rains in March occurred over the northern and western sector of the region, including much of Yemen, Djibouti, Ethiopia, southern South Sudan, Uganda, western and some central counties of Kenya, and over pastoral regions of Ethiopia, northern Kenya, and Somalia. In contrast, Rwanda, northern Burundi, Tanzania, and southern Kenya have observed significantly delayed onsets of 20-30 days, and portions of southern Kenya and southern Somalia have yet to experience the establishment of the seasonal rains.

    March rainfall was abnormally heavy in most areas (Figure 1), mainly attributed to the passage of an atmospheric perturbation known as the Madden Julian Oscillation (MJO). These rains were associated with flash floods in Kisumu, Nairobi, and Marsabit in Kenya; Borena in Ethiopia; and southern Somalia (due to high Juba River levels). On the other hand, significant early season rainfall deficits were recorded in eastern areas of Tanzania, Kenya, and on the periphery of western Ethiopia. This is due to the adverse impacts of tropical cyclone Freddy, which diverted moisture and associated heavy tropical rains into Mozambique, Malawi, and the neighboring southern African countries.

    Figure 1

    CHIRPS cumulative rainfall, March 1-31, percent of 1981-2020 average
    Map showing above-average rainfall was received over most of the region, except coastal parts of Kenay and Tanzania

    Source: UC Santa Barbara Climate Hazards Center

    Current satellite-derived vegetation anomalies reveal significant improvement in greenness of vegetation including pasture in the northern sector of the region – especially Yemen, Djibouti, and parts of central and northern rift valley regions of Ethiopia and into South Sudan – in response to the recent moderate to very heavy rains (Figure 2). The full beneficial impacts of the ongoing rains on vegetation conditions are likely to become more evident in coming weeks across much of East Africa. However, vegetation conditions in coastal regions of northern Tanzania and southern Kenya are expected to remain generally drier-than-normal given current and forecast rainfall conditions.

    Figure 2

    e-MODIS Normalized Difference Vegetation Index (NDVI), percent of the 2003-2017 median, March 21-31, 2023
    Map showing below-average vegetation in most of the region, but above-average vegetation in much of South Sudan, northwestern Ethiopia, and Yemen

    Source: USGS/FEWS NET

    Surface water resources have also been significantly replenished and are generally nearly at bankfull levels. This includes some seasonal rivers in pastoral and parts of agropastoral livelihood zones in the eastern Horn, where the rains have been heavy to very heavy. However, these surface water resources are subject to siltation due to high run-off, resulting in poor quality of water for human and livestock consumption.

    While the above-average rainfall received in March was overall a welcome short-term relief for most of the worst drought-affected areas of the eastern Horn, some areas experienced the negative impacts of severe flooding, which damaged property and killed livestock. Additionally, it should be emphasized that full recovery from the historic five-season drought in the region – which devastated livestock herds and highly degraded environmental conditions – will take several seasons or even years of good rainfall performance.

    The following is a country-by-country update on recent seasonal progress to date:

    • In Somalia, the Gu rains are yet to be fully established as they typically start in early to mid-April. However, recent unusually heavy rainfall in southern Somalia along the border with northern Kenya/southeastern Ethiopia has resulted in high Juba River levels that caused flooding in cropland and residential areas in Bardheere district (Gedo region), destroying standing off-season crops along the depressed lands. However, it also contributed to improvements in localized pasture and water resources. Overall, rangeland resources remain drier-than-normal in many parts of southern and central Somalia and are expected to remain fairly poor until after the start of seasonal rains in mid-April. This delayed improvement is due to the prolonged drought and exceptionally hotter-than-normal conditions, which have resulted in atypical livestock migration (from within and outside of Somalia) and over-grazing in the few areas where green or dry pasture is still available. Livestock body conditions and productivity are largely below average to poor in many areas.
    • In Ethiopia, for the past month, the Belg/Gu/Genna seasonal rains have largely been characterised by early to timely onset and above-average rainfall performance, generally supporting cropping conditions. However, over the Belg-receiving regions of southwestern and western Ethiopia, the long rains (March-November) have been delayed by 2-3 weeks. Improved vegetation conditions and replenishment of water resources are now evident across much of Ethiopia following the March rains, expected to be providing relief for pastoral communities in these areas. However, flash floods and livestock losses were reported in many parts of eastern Ethiopia – including parts of Addis Ababa city, Afar, eastern Oromia, and central and northern Somali regions, with more severe floods in southern and eastern Somali, Borena, and Konso regions. On the other hand, Belg-receiving parts of Gambela and Oromia regions are showing signs of increasing rainfall deficits and below-average vegetation conditions.
    • In Kenya, the 2023 long rains season (March to May in bimodal areas; March to November in unimodal areas), began 10-20 days earlier than normal over the northern, rift valley, and central counties of Kenya. However, full onset of rainfall was delayed by 20-30 days around the Lake Victoria basin and southwestern counties of the country, which is likely to delay planting activities. There are increasing concerns for continued early season rainfall deficits and delayed onset of rains over localized portions of the southeastern lowlands and coastal strip. Flash floods are likely to continue over southwestern counties of Kenya and in urban areas with poor drainage systems given forecasts of above-average rainfall in the coming weeks, especially in central and western Kenya. In unimodal major agricultural areas, land preparation is underway for long rains maize and rice crops, and planting will begin in April. In the bimodal areas of central and southeastern Kenya, planting of long rains cereal crops is underway, with concern in the southeastern marginal agricultural areas as the seasonal rains have been delayed and below-average.
    • Sudan remains typically dry in the dry season, but with hotter-than-normal conditions. Presently, the vegetation conditions in the country are largely normal to greener-than-normal along the Nile basin and surrounding areas. Little or no rains are forecast in April for much of the country.
    • In South Sudan, ongoing first season rains have been characterized by an early onset in southern and western regions of the country, with above-average rainfall amounts in March. Vegetation conditions are expected to be significantly greener-than-normal in response to recent heavy rains. However, localized areas in parts of eastern Jonglei State bordering Ethiopia experienced early season rainfall deficits. Cropping conditions are currently favorable (with crops in emergence stage) and likely to remain so in the coming weeks in most parts of South Sudan, despite forecast dry spells by mid-April. Risk of flooding is likely to remain low during this period.  
    • In Uganda, bimodal northern and southern regions of the country experienced an early onset of the seasonal rains in early to mid-March, with mostly favorable cropping conditions. Crops are generally at emergence to early vegetative stages. Meanwhile, much of the rest of the country (central and western regions) experienced a timely to slightly delayed onset of the rains and planting. Overall, cumulative rainfall in March was unexpectedly well above average (more than 150 percent of average) in much of the northern region including unimodal Karamoja, and average to above average to elsewhere in the country. As such, vegetation conditions are generally exceptionally greener-than-normal in most parts of the country.  However, flooding was reported in northern and central districts, including Kampala. Though crop conditions are currently favorable, there are concerns for poorly distributed rainfall and dry spells in the coming weeks, especially in northern and eastern regions.
    • In Rwanda and Burundi, there has been mixed early season rainfall performance. South-central Burundi experienced a timely onset of rains, but much of Rwanda and northern Burundi experienced a significantly delayed onset (20 – 30 days). Both countries experienced above-average rainfall amounts in March, with some flooding reported in Burundi. However, there is increasing likelihood of below-average rainfall in Rwanda in early to late April. Cropping and vegetation conditions are near average and likely to improve further with ongoing seasonal rains.
    • In Yemen, the March – May seasonal rains started with above-average rainfall received across the country. Vegetation conditions are greener-than-normal, particularly over the western highlands and coastal regions. Across much of the central and eastern regions, vegetation conditions are near average, with average land-surface-temperatures.


    Figure 3

    IRI/CPC Sub-X rainfall probability forecast, valid between, April 8 - 21, 2023
    Map showing below-average rainfall most likely over much of the region, but above-average rainfall most likely in Yemen and northern Ethiopia and Somalia

    Source: IRI/CPC

    Figure 4

    Cumulative rainfall forecast for March 1 – April 25, 2023, expressed as percent of the 1981-2020 average; based on CHIRPS final data for March 01-31, CHIRPS prelim data for April 1-10, and unbiased GEFS forecast for April 11-25
    map showing above-average rainfall expected over most of the region, though below-average rainfall is expected over parts of central Somalia, southern Kenya, and northeastern Tanzania

    Source: UC Santa Barbara Climate Hazards Center

    In the coming weeks, the March – May rains are forecast to be fully established across East Africa, facilitating the establishment of planting activities. According to the IRI/CPC sub-seasonal (sub-X) probability forecast for April 8 - 21, rainfall during this period is likely to be above average in Yemen, northern Somalia, Djibouti, and Eritrea (Figure 3). Meanwhile, there is an elevated likelihood of below-average rainfall in much of Uganda, southern South Sudan, Rwanda, western Kenya, and East Africa’s coastal strip (Somalia, Kenya, and Tanzania).  The rest of the region is expected to experience average rainfall and land surface temperatures. Above-average cumulative seasonal rainfall totals are likely to be sustained across large portions of the region through late April (Figure 4). However, below-average cumulative totals are expected in much of south-central Somalia and coastal areas of Tanzania and Kenya. There is also increasing concern that peak April rains are likely to be unevenly distributed in time and space. Typically, most coastal areas experience their rainfall peak in May/June, which is likely to be average given the influence of the positive IOD forecast during this period.

    Rangeland resources are anticipated to gradually and significantly improve in the coming weeks for much of the drought-affected pastoral zones of eastern East Africa. However, given the devastating impacts of the five-season drought, livelihoods are unlikely to fully recover from these early to mid-season rains. Conditions in key cereal cropping areas in Uganda, western Kenya, and parts of southwestern Ethiopia are generally anticipated to remain favorable, but performance is likely to be mixed over agropastoral zones of southern Somalia, southeast Kenya, and neighboring northeastern regions of Tanzania.

    FEWS NET’s Seasonal Monitor reports are produced for Central America and the Caribbean, West Africa, East Africa, Central Asia, and Somalia every 10-to-30 days during the region’s respective rainy season(s). Seasonal Monitors report updates on weather events (e.g., rainfall patterns) and associated impacts on ground conditions (e.g., cropping conditions, pasture and water availability), as well as the short-term rainfall forecast. Find more remote sensing information here.

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