This study examines the improvement in Coupled Model Intercomparison Project Phase Six (CMIP6) models against the predecessor CMIP5 in simulating mean and extreme precipitation over the East Africa region. The study compares the climatology of the precipitation indices simulated by the CMIP models with the CHIRPS data set using robust statistical techniques for 1981–2005. The results display the varying performance of the general circulation models (GCMs) in the simulation of annual and seasonal precipitation climatology over the study domain. CMIP6 multi‐model ensemble mean (hereafter MME) shows improved performance in the local annual mean cycle simulation with a better representation of the rainfall within the two peaks, especially the MAM rainfall relative to their predecessor. Moreover, simulation of extreme indices is well captured in CMIP6 models relative to CMIP5. The CMIP6‐MME performed better than the CMIP5‐MME with lesser biases in simulating Simple Daily Intensity Index (SDII), consecutive dry days (CDD), and very heavy precipitation days >20 mm (R20mm) over East Africa. Remarkably, most CMIP6 models are unable to simulate extremely wet days (R95p). Some CMIP6 models (e.g., NorESM2‐MM and CNRM‐CM6‐1) depict robust performance in reproducing the observed indices across all analyses. OND season shows wet biases for some indices (i.e., R95p, PRCPTOT), except for SDII, CDD, and R20mm in CMIP6 models. Consistent with other studies, the mean ensemble performance for both CMIP5/6 shows better performance as compared with individual models due to the cancellation of some systematic errors in the individual models. Generally, CMIP6 depicts improved performance in the simulation of MAM rainfall compared with CMIP5 models. However, the new model generation is still marred by uncertainty, thereby depicting unsatisfactory performance over the East Africa domain. This calls for further investigation into the sources of persistent systematic biases and a methodology for identifying individual models with robust features that can accurately simulate observed patterns for future usage.

This paper presents an analysis of projected precipitation extremes over the East African region. The study employs six indices defined by the Expert Team on Climate Change Detection Indices to evaluate extreme precipitation. Observed datasets and Coupled Model Intercomparison Project Phase six (CMIP6) simulations are employed to assess the changes during the two main rainfall seasons: March to May (MAM) and October to December (OND). The results show an increase in consecutive dry days (CDD) and decrease in consecutive wet days (CWD) towards the end of the 21st century (2081–2100) relative to the baseline period (1995–2014) in both seasons. Moreover, simple daily intensity (SDII), very wet days (R95 p), very heavy precipitation >20 mm (R20 mm), and total wet-day precipitation (PRCPTOT) demonstrate significant changes during OND compared to the MAM season. The spatial variation for extreme incidences shows likely intensification over Uganda and most parts of Kenya, while a reduction is observed over the Tanzania region. The increase in projected extremes may pose a serious threat to the sustainability of societal infrastructure and ecosystem wellbeing. The results from these analyses present an opportunity to understand the emergence of extreme events and the capability of model outputs from CMIP6 in estimating the projected changes. More studies are recommended to examine the underlying physical features modulating the occurrence of extreme incidences projected for relevant policies.

Rainfall extremes can cause a significant loss of lives and economic losses in Nigeria. This study aims to investigate the trends of summer rainfall extremes over Nigeria with daily station datasets from 1975 to 2013. Using the rainfall extreme indices recommended by the Expert Team on Climate Change Detection Monitoring Indices (ETCCDMI), it is found that regionally averaged summer total wet-day rainfall amount (PRCPTOT), maximum consecutive 5-day rainfall amount (RX5day), and wet-day rainfall intensity (SDII) have increased in the three climatic regions of Nigeria namely Guinea coast, Sub-Sahel, and the Sahel regions. Meanwhile, heavy rainfall days (R20mm) increased significantly over the Guinea coast and sub-Sahel regions, while the wet-day frequency (RR1) only increased slightly. The increase in PRCPTOT over the two regions is mainly resulting from the increasing intensity and frequency of rainfall extremes. However, the Nigerian Sahel is characterized by a decreasing wet-day frequency, which demonstrates that a large proportion of the increasing PRCPTOT in the region is more associated with intense rainfall than its frequency. These characteristic increasing trends of rainfall extremes may explain the frequent flood events over Nigeria and as such this study may give guidance to stakeholders on how best to cope with it in the future.

The present precipitation and temperature patterns and expected future changes (2073–2098) in Africa are investigated using the Hadley Centre Global Environmental Model 2‐Earth System (HadGEM2‐ES) under the fifth phase of the Coupled Model Intercomparison Project (CMIP5) protocols for historical and future emission scenarios simulations. In a CMIP5 multimodel analysis, the annual cycles of temperature and precipitation simulated by HadGEM2‐ES were very close to the multimodel ensemble mean. HadGEM2‐ES temperature simulation compares well with the National Center for Atmospheric Research (NCAR) reanalysis over the 1979–2004 periods, except for a summer overestimation in Central Africa, and a winter underestimation in tropical West Africa. The precipitation simulation compared well with the Global Precipitation Climatology Project (GPCP) data from 1979 to 2004 over the entire Africa, except in the Intertropical Convergence Zone (ITCZ), where the model fails to capture adequately the transition phase of the monsoon circulation. The dry regimes over Northern Africa as well as the wetter regime occurring over Central Africa, which is mainly regulated by the ITCZ displacement, and during the austral summer of Southern Africa, are also fairly reproduced by the HadGEM2‐ES model. The model projects for the end of the 21st century a rainy South Africa, a change of the flood/drought cycle in the Tropics and a warming over the whole continent, varying from 3 to 7 °C. HadGEM2‐ES performance for Nigeria shows good reproduction of precipitation seasonal cycles for some locations, outside the ITCZ. However, the comparison within situmeasurement in Ilorin and Lagos shows the model is not being able to reproduce the precipitation annual cycle. Future projections for Nigeria exhibit warming everywhere and an enhancement of precipitation, especially in the northern part of the country.