Pendjari has a hard seasonal calendar: the park is generally open from mid-December to mid-May and closes through the rains. The single best window is March and April, when the bush is at its driest, the waterholes have shrunk to a few key pools, and game concentrates in predictable places. Early in the season (December–January) is greener and prettier but animals are dispersed and harder to find.
Avoid the harmattan haze of late December and January if photography matters to you — the air can be thick with dust off the Sahel and visibility drops sharply. Daytime temperatures climb steeply from February onwards; by April, midday in the park is well over 40°C and game drives are dawn-and-dusk only. From mid-May the rains start in earnest, tracks become impassable, and the park closes.