Saint-Louis weather in May

Saint-Louis's own Tripadvisor forum doesn't have much September-specific weather discussion, so this is grounded in the destination's real climate record rather than a traveler account: this is the tail end of Senegal's rainy season, with hot, humid days in the low 30s C and a real but not overwhelming chance of rain most days. Evenings stay warm too, so it's worth planning riverside walks or boat trips for the cooler morning hours rather than midday. The wet season here is milder than further south in West Africa, so it shouldn't be a dealbreaker for a visit.

Forum posters describe March as sitting within Senegal's dry season along the coast, with daily temperatures generally between 25-32C and low humidity typical for the season - conditions posters describe as comfortable for sightseeing. Posters do flag that some years bring a Harmattan-driven dusty, hazy stretch with a notably brown sky even in March, a real possibility to prepare for even during the otherwise dry, sunny season. Posters note that temperatures and humidity climb noticeably once you head inland away from Saint-Louis' coastal position, so the city itself should stay comparatively milder than destinations further from the Atlantic during the same March visit.