Daily rainfall records for 1961–1990 for Nguru (12.53°N, 10.28°E, alt. 343 m), Potiskum (11.42°N, 11.02°E, alt. 415 m) and Maiduguri (11.51°N, 13.05°E, alt. 354 m) in Nigeria and Maine Soroa (13.13°N, 11.58°E, alt. 339 m) in Niger were analysed to describe any changes in season duration, rain-days per season and rainfall amount per rain-day. There was a consistent decrease in annual rainfall of 8 mm year−1 at all four stations. The majority of this reduction occurred in August or September. Although there was a delay in the onset of the rains at the two westernmost stations, the main reason for the decrease in rainfall was a reduction of 6–25 days in the number of rain-days during the rainy season. This increased the mean duration of dry spells during the rainy season by up to 1.5 days. No change in the average rainfall per rain-day was detected except at Maine Soroa where there was a slight reduction. The results are discussed in terms of their implications for sustainable agriculture in the region.