This review examines several aspects of the climate of eastern Africa. The climatic commonality throughout the region is the frequent occurrence of drought severe enough to incapacitate the population. Because of recent droughts and evidence of disastrous, long‐term climatic change, the region has become a major focus of meteorological research. This review covers six relevant topics: climatic regionalization, seasonal cycle, intraseasonal variability, interannual variability, recent trends, and seasonal forecasting. What emerges is a markedly different view of the factors modulating rainfall, the dynamics associated with the seasons, and the character of teleconnections within the region and the interrelationships between the various rainy seasons. Some of the most important points are the following. (1) The paradigm of two rainy seasons resulting from the biannual equatorial passage of the Intertropical Convergence Zone is inadequate. (2) The “long rains” should not be treated as a single season, as character, causal factors, and teleconnections are markedly different in each month. (3) The long rains have been declining continuously in recent decades. (4) The Madden‐Julian Oscillation has emerged as a factor in interannual and intraseasonal variability, but the relative strength of Pacific and Indian Ocean anomalies plays a major role in the downward trend. (5) Factors governing the short rains are nonstationary. (6) Droughts have become longer and more intense and tend to continue across rainy seasons, and their causes are not adequately understood. (7) Atmospheric variables provide more reliable seasonal forecasts than the factors traditionally considered in forecast models, such as sea surface temperatures and El Niño–Southern Oscillation.

The common explanation for the progression of the rainy season over Africa is the seasonal excursion of the ITCZ. The ITCZ paradigm stems from a time when tropical rainfall was assumed to be associated mainly with localized convection. Its development was also linked to the emergence of midlatitude frontal concepts. The paradigm has numerous shortcomings, including the diversity of definitions and the large number of parameters used to identify the ITCZ. A historical look at the concept shows that its use over Africa has long been controversial, with many eminent tropical meteorologists harshly criticizing its applicability over this continent. However, the seasonal excursion of the ITCZ remains the classical explanation for African rainy seasons, especially in the equatorial region. This article underscores the shortcomings of the paradigm in equatorial Africa by examining various aspects of the circulation associated with the spatial and temporal patterns of rainfall during the equatorial rainy seasons. The overall conclusion is that a deeper understanding of the seasonal cycle in the equatorial regions of Africa still needs to be developed.

This study utilizes a new 139‐year rainfall record for East Africa to evaluate the relationship between the ‘short rains’ of October–November and four tropical indices. These indices include the zonal winds at the surface and 200 mb over the central equatorial Indian Ocean, Niño 3.4 and the Indian Ocean Zonal Mode (IOZM). The relationships with these indices are time dependent, as are the relationships among the indices. These change markedly on a decadal timescale, consistent with regime changes indicated by other authors, and the links to El Niño‐Southern Oscillation (ENSO) and the IOZM appear to be weaker than those suggested by previous studies. The zonal winds show the strongest and most consistent relationships with October–November rainfall. However, the relationships are very different for wet and dry years, and the zonal winds play a stronger role in producing wet conditions. Further, several factors appear to act in tandem to produce extremely wet years, but appear to act largely independently in producing drought. The links to drought have been markedly weaker since 1982. These links were also very weak roughly between 1920 and 1960, when apparently the Walker cell over the Indian Ocean was very weak and the Pacific Walker cell particularly strong. At that time, ENSO appeared to drive most of the variability of October–November rainfall, interannual variability was weak, and the rainfall was below average during most of that period. When the zonal circulation in the Indian Ocean sector became well‐developed c. 1961 and the Pacific cell weakened, both the rainfall and its interannual variability markedly increased. Overall, this study stresses the time dependence of the various relationships with East African October–November rainfall. This has strong implications for seasonal forecasting.

A wealth of historical information on climate and weather exists for the African continent. Documentary information, hydrologic indicators, and rain gauge records have been compiled and combined into a semiquantitative precipitation dataset that extends from 1801 to 1900. That dataset describes “wetness” for 90 regions of Africa, using a seven-category index. A regional gauge dataset for 1901–2000 has been converted to the seven-class system, extending coverage to two centuries. These datasets are available through the Paleoclimate Data Center.

A growing number of proxy, historical and instrumental data sets are now available from continental Africa through which past variations in temperature can be assessed. This paper, co-authored by members of the PAGES Africa2k Working Group, synthesises published material to produce a record of temperature variability for Africa as a whole spanning the last 2000 years. The paper focuses on temperature variability during the ‘Medieval Climate Anomaly’ (MCA), ‘Little Ice Age’ (LIA) and late 19th–early 21st centuries. Warmer conditions during the MCA are evident in records from Lake Tanganyika in central Africa, the Ethiopian Highlands in northeastern Africa, and Cango Cave, the Kuiseb River and Wonderkrater in southern Africa. Other records covering the MCA give ambiguous signals. Warming appears to have been greater during the early MCA (c. ad 1000) in parts of southern Africa and during the later MCA (from ad 1100) in Namibia, Ethiopia and at Lake Tanganyika. LIA cooling is evident in Ethiopian and southern African pollen records and in organic biomarker data from Lake Malawi in southeastern tropical Africa, while at Lake Tanganyika the temperature depression appears to have been less consistent. A warming trend in mean annual temperatures is clearly evident from historical and instrumental data covering the late 19th to early 21st centuries. General warming has occurred over Africa since the 1880s punctuated only by a period of cooling in the mid 20th century. The rate of temperature increase appears to have accelerated towards the end of the 20th century. The few long high-resolution proxy records that extend into the late 20th century indicate that average annual temperatures were 1–2°C higher in the last few decades than during the MCA.

This article develops the first climatology of the low‐level jet that prevails in the Turkana Channel of northern Kenya. ERA‐Interim data are utilized, giving the analysis a resolution of 0.75° of latitude/longitude and a temporal resolution of 6 h. The jet is found to be a semi‐permanent feature, its occurrence ranging from 69% of the days in May to 90% of the days in October. It is strongest during the June–September dry season. Typical core speeds in a 0.75 × 0.75 grid point are 10–15 m s⁻¹. The Turkana Jet is clearly a nocturnal feature, being strongest at 0000 UTC or 0600 UTC and usually barely discernible at 1200 UTC. There are distinct patterns of divergence and vertical motion associated with the jet and these differ between the entrance, core, and exit regions. The jet appears to modulate rainfall, especially during the nocturnal hours, with strong jets suppressing rainfall. It also appears to be a factor in the prevailing aridity in the northeast Kenya, southern Somalia, and southeastern Ethiopia and the absence of a summer rainy season in this region.