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June to September 2020 rains marked by extensive flooding and historically high water levels

  • Seasonal Monitor
  • East Africa
  • October 10, 2020
June to September 2020 rains marked by extensive flooding and historically high water levels

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  • Key Messages
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    Key Messages
    • The June to September 2020 seasonal rains over the northern and western sector of the region were above average across much of the region. Devastating floods occurred at the peak of the rainfall season, affecting over 2.5 million people and causing significant crop damage in riverine areas in Sudan, South Sudan, Yemen, Ethiopia, Somalia, Uganda, and Kenya.

    • Crop losses were significant in several riverine areas, including along the Awash River in Ethiopia, the While and Blue Nile Rivers in South Sudan and Sudan, and the Juba and Shabelle Rivers in Somalia. Outside of flood-affected areas, the seasonal rains were generally beneficial for crop and livestock production, water availability, and hydro-power generation across East Africa. The water-levels in major lakes, rivers, and dams are among the highest on record, especially in the Lake Victoria basin, major Rift Valley lakes, and White and Blue Nile Rivers.

    • Desert locust swarms continue to form, and breeding is underway in Ethiopia, north-central Somalia, Yemen, and eastern Sudan. The situation in Ethiopia is of high concern, where government and other sources report significant damage to meher crops in Amhara, Tigray, and Oromia regions.

    • Rangeland resources and livestock production conditions are exceptionally above average across most pastoral and agropastoral regions of East Africa due to two consecutive rainfall seasons of above average rainfall performance since late 2019. However, atypically high disease prevalence and livestock deaths are reported in South Sudan due to severe floods in 2019 and 2020.

    • The 1-2 weeks rainfall outlook depicts the gradual southward shift of the tropical rainfall system from the northern to equatorial sectors. This marks a timely onset of the seasonal rains in bimodal South Sudan and Uganda, while the rains will gradually subside and reduce the risk of associated flooding in Sudan, unimodal South Sudan, Yemen, and Ethiopia. However, much of eastern Horn is expected to remain sunny and dry, with a delayed and erratic onset of the short/deyr rains in eastern Ethiopia and southern Somalia.


    The June to September 2020 seasonal rains ranged from 105 to more than 145 percent of average in Yemen, Ethiopia, Sudan, eastern South Sudan, Uganda, and western Kenya (Figure 1). Rainfall was historically high in Yemen's western highlands and coastal regions, where the rains were among the wettest on record and ranged between 200 and 400 percent of the long-term average. Rainfall was also historically high in parts of southwestern Ethiopia and western Kenya, reaching 150-200 percent of the long-term average.

    The atypically heavy rains from July to late September resulted in floods in many areas of East Africa and Yemen. Many of these areas already had above-average river and lake water levels and above-average soil moisture levels due to heavy rains in late 2019 and early 2020. According to UNOCHA and other sources, the floods caused human fatalities, displacement, and property damage. In the countries that were worst affected by flooding, the number of affected people includes at least 875,000 people in Sudan, 625,000 people in South Sudan, 1,017,854 people in Ethiopia, and 96,000 households in Yemen. Additionally, several thousand people were affected in Kenya and Uganda. In October, the tropical rainfall system is beginning to gradually shift southward to the equatorial sector of East Africa, indicating that the rains and associated floods should start to subside in Yemen, Ethiopia, and Sudan.

    The floods caused significant damage to crop production in several riverine areas, including along the Awash River in central Oromia and Afar regions of Ethiopia, along the White Nile River in eastern and northern South Sudan, and along the Shabelle River and the lower Juba River in southern Somalia. Parts of Sudan, especially Gezira and Kassala states, have also been significantly affected. In other parts of the region, however, the rains were generally beneficial for agricultural production. The early to timely onset of the seasonal rains in June, coupled with sufficient crop soil moisture throughout the cropping season, has facilitated favorable yield prospects in Ethiopia, Sudan, South Sudan, western and central Rift Valley areas of Kenya, and parts of northern and eastern Uganda. However, desert locust infestations in agropastoral areas of northern Ethiopia and northwestern Somalia have contributed to some production losses. In South Sudan, damage from desert locust in the southeast and Fall Army Worm in the northwest is relatively low.

    Consecutive seasons of average to above-average rainfall from mid-2019 to mid-2020 have generally had more significant benefits for livestock production. According to remote sensing imagery, vegetation conditions in early October remain normal to above normal in most of Kenya, Ethiopia, and northern Somalia as well as in Sudan, South Sudan, and Uganda. Although desert locusts have damaged pasture in northern and eastern Ethiopia, northern and central Somalia, and northwestern Kenya, the rains have supported pasture regeneration and typical migration options. However, the floods have caused atypical livestock migration, increased disease prevalence, and loss of pasture in areas experiencing more severe flooding, including South Sudan. Meanwhile, there are localized areas of below-normal vegetation conditions in parts of eastern Sudan and South Sudan due to dryness or due to over-saturation. The ongoing dry season has also led to below-normal vegetation in central and southern Somalia and the coastal strip of southern Kenya and northern Tanzania. Western Tanzania, Rwanda, and Burundi are also drier than normal due to a delay in the start of the September-December seasonal rains.

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

    • In Somalia, June to September rainfall was above average in northwestern Somalia and mixed in southern and central Somalia. The only areas that receive significant rainfall in Somalia during this period include the northwest, which receives karan rains, and the southern coastal regions that receive hagaa rains. Most of the rest of the country was typically dry and hotter-than-average. Rangeland resources remain favorable in the north, but relatively drier-than-normal vegetation conditions are observed in parts of central and southern Somalia due to the early start of the dry season in May/June. Currently, the start of the deyr rains in October are delayed and yet to be fully established. Based on the short-term forecast, there are indications of early season deficits. Meanwhile, Desert Locust is mainly present in north-central Somalia, where the impact on crops and rangeland is generally low. However, the seasonal shift in the northeasterly surface winds presents a risk that locusts will spread to central and southern regions.
    • In Ethiopia, meher crop production in western Ethiopia is expected to be below average. Although rainfall during the June to September kiremt season was generally beneficial to agricultural production and water availability, crop production has been negatively affected by desert locust and reduced access to inputs at the farm level. Desert locust continue to be of high concern, with swarms spreading in Afar, Tigray, Amhara, and Somali regions. However, livestock production is performing well due to the impact of enhanced rains since 2018. In flood-affected areas, the heavy kiremt rains caused unprecedented flooding, affecting over one million people, of whom nearly 300,000 were displaced. According to UNOCHA, the worst-affected regions include Oromia (447,565 people), Amhara (144,490 people), Somali (140,892 people), and SNNPR (90,121 people). The floods also damaged 60,000 hectares of croplands.
    • In Kenya, June to September rainfall ranked among the wettest periods on record in much of Kenya’s western and Rift Valley areas. Rainfall in parts of central Kenya were also above average. The rains led to favorable cropping conditions for main season crop production in key maize producing areas of the Rift Valley and western Kenya, leading to average to above-average production prospects. In contrast, pastoral and agropastoral areas across the rest of the country are seasonally dry but hotter than normal. However, this has not had adverse impacts on rangeland resources due to accrued gains from above-average rains in late-2019 into mid-2020. Currently, the start of the short rains season in October is underway in the west, but the rains have yet to be established in eastern and northern Kenya.
    • In Sudan, atypically heavy rains during the June to September season led to severe flooding across much of central and eastern Sudan, as the White and Blue Nile rivers reached record-high levels. An estimated 875,000 people have been affected by the floods since July, with at least 120 fatalities. The worst flood-affected states include Gazira, Kassala, northern and western Darfur, and Sennar. Although desert locust development and breeding is of high concern in the east and southern coast, a multi-agency desert locust impact assessment conducted in July found that damage to crops damage is low thus far due to effective monitoring and efficient response. Crop production is expected to be average to above average and almost comparable to the 2019 season, except in localized cropping zones that are still inundated.
    • In South Sudan, UNOCHA and WFP reports place estimates of flood-affected people at 625,000-700,000 people due to above-average rainfall during the June to September season. Rainfall continues to be heavy in October. The worst-affected areas include Jonglei (230,000 people), Lakes (147,000 people), and Unity (83,000). At least 21,000 people have been displaced from Jonglei to Mingakaman in Awerial county of Lakes, primarily due to flooding. In October, the seasonal rains are continuing and there is an elevated flood risk in riverine and wetland areas. Although cropping and rangeland conditions have remained very good throughout the season, the floods have led to significant crop losses along the Nile River basin and in eastern South Sudan more broadly. Although desert locust damage was reported in the southeast and Fall Army Worm damage in the northwest, key informants currently report that the impacts to crops are low.
    • In Uganda, seasonal rainfall from June to September in Karamoja and parts of northern and central Uganda were above average. Due to early-season waterlogging, crop production in Karamoja is anticipated to be average to slightly below average. Meanwhile, rangeland and water resources are generally near normal, though overgrazing is reported in some cattle corridor areas. Desert locusts are not currently present in Uganda and the damage reported in parts of the north and northeast is minimal. Currently, the second season rains have already begun and are expected to be fully established within the coming weeks, prompting land preparation and planting in bimodal areas. Persistent rainfall continues to result in heightened flood risk over the Lake Victoria basin and its environs, the Mt. Elgon region, Lake Albert basin, and northern districts.
    • In Rwanda and Burundi, conditions remained typically sunny and dry from June to September. The early start of the dry season in May/June has led to drier-than-normal vegetation conditions in parts of northern Rwanda. Currently, the start of the September to December Season A rains is delayed by 20-30 days, resulting in early-season deficits, especially in northern Rwanda. However, the short-term forecast indicates an increased likelihood that the Season A rains will be established in late October.
    • In Yemen, record-high rainfall from June to September led to significant flooding that affected at least 96,000 households in western and coastal Yemen. However, flood waters have now receded following a decrease in rainfall in September. Vegetation conditions across the country are exceptional, especially over the western highlands and coastal regions. In October, localized light to moderate rains are anticipated across the portions of the western sector as the seasonal rains subside, marking the onset of the dry season.


    According to the short-term rainfall forecast through October 21st, there is an increased likelihood of moderate to heavy seasonal rainfall over southern South Sudan, western and southern Ethiopia, parts of south-central Somalia, and Uganda, Rwanda, and Burundi (Figure 3). This marks the establishment of the October to December 2020 rainfall season in bimodal areas. Rainfall will also continue in western Kenya. However, many areas in the eastern Horn of Africa and Tanzania are forecast to remain sunny and atypically hot, especially in Kenya. This is consistent with seasonal forecasts that the October to December rains will be delayed, erratic, and below average.

    Over the coming weeks, the gradual southward shift of the tropical rainfall system is expected to lead to a declining likelihood of flooding in the northern sector of the region. Flood events should subside significantly and give way to sunny and dry conditions over Sudan, northern and eastern Ethiopia, and northern and northwestern South Sudan. However, an elevated risk of flooding is likely to persist in areas surrounding the Lake Victoria and Lake Albert basins in Uganda, Mt. Elgon on the Kenya/Uganda border, northern Uganda, southeastern South Sudan, and southwestern Ethiopia.

    A review of the cumulative rainfall performance for September and early October together with forecast mid-October rainfall anomalies depicts the erratic onset of the short/deyr rains over the Somali region of Ethiopia and parts of central Somalia (Figure 4). Early season rainfall deficits are also evident of parts of eastern Tigray and Oromia as well as western Somali region and southern Somalia, including the Kenya and Somalia coastal strip. However, much of western sector of the region is expected to receive timely and above average rainfall amounts in coming weeks, including the Lake Victoria region, northern Uganda, and southern South Sudan. Eastern Horn pastoral and agro-pastoral regions are unlikely to receive any significant rains in the next 1-2 weeks, as typically common in these areas, until late October into early November. The consensus regional forecast was indicative of erratic and delayed onset of the seasonal rains over much of eastern Horn, especially in pastoral and marginal agricultural areas. Following the retreat of tropical rain systems toward the equator and the reversal of southwesterly wind flow into northeasterly wind flow, conditions are expected to be conducive for further southward migration of desert locusts, especially from northern Ethiopia into southeastern Ethiopia and from northern Somalia into central Somalia.

    Figures Map of East Africa showing rainfall accumulation from June to September 2020 as a percent of the long-term average

    Figure 1

    Figure 1

    Source: FEWS NET

    Map of East Africa showing vegetation conditions in late September as a percent of median

    Figure 2

    Figure 2

    Source: FEWS NET

    Map of East Africa showing the rainfall forecast through October 21

    Figure 3

    Figure 3

    Source: NOAA/CPC

    Map of East Africa showing current and forecast rainfall from September 1 to October 25 as a difference from the long-term av

    Figure 4

    Figure 4

    Source: UC Santa Barbara Climate Hazards Center

    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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