The time series plot show that the short-rains fell in abundance during much of the 20th century, notably during the latter half. The climate models project a regular upward trend from the early years of the 21st century, persisting throughout the entire century. Consistent with this trend is a positive shift of the entire rainfall distribution in these areas (less severe droughts and more intense wet seasons).
From the long-rains time series plot, it is evident that an out-of-phase low-frequency pattern of variation with the second season rains is possible. For instance, the rainfall deficits which started to befall this region from the 1970s persisted longer during MAM season (extending up to the 1990s). There has been a recovery during the very last years of the 20th century, which is projected by the models to continue in the form of a steep wettening trend during most of the 21st century. Note however that the signal-to-noise ratio in the model projections for this season is comparatively low.
Northeastern Kenya is semi-arid with a bimodal rainfall regime. The peaks (~2mm/day) occur around April and November. Almost all the models overestimate the amplitude of the 20th century annual cycle in this area. Without exception, modelled rainfall amounts during the short-rains are notably high. An increase in mean monthly precipitation is projected by all the models during the peaks of the rainfall seasons. A few (HadGEM1, ECHO-G, HadCM3 and GFDL CM2.1) give indications for an earlier termination of the long rains (lesser precipitation in May). However, the models show less realism in simulating the rainfall interannual variability during this season. Consequently, these modelled results are less reliable.