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Rainfall in the Nigerian Guinea Savannah has become less predictable in onset and distribution over the past fifteen years, with consequences for rain-fed smallholder agriculture. This study examines the relationship between intra-seasonal rainfall variability and maize yields across four states between 2010 and 2024. Daily rainfall records from twelve stations were combined with plot-level yield returns from 480 smallholder farms. We find that total seasonal rainfall is a weak predictor of yield, while the length of the longest dry spell during the tasselling window explains a substantially larger share of the variation. Farms that adjusted planting dates in response to observed onset recorded smaller losses than those planting on fixed calendar dates. The findings suggest that advisory services should prioritise dry-spell forecasting and flexible planting guidance over seasonal rainfall totals alone