Cotonou weather in December

Lagos, Nigeria sits squarely in harmattan season by December — the dry, dusty wind that peaks across West Africa from December through February — but that doesn't mean cool or comfortable. One traveler's review of a December visit is blunt about it: the humid heat hit them hard as sweat poured down their heads, heat and humidity together rather than the drier air harmattan brings further inland. The dry season does mean less rain than the rest of the year, but the trade-off is dust haze from the wind rather than clear skies. Our record: 31.2°C days, 76.5% humidity, only 10 rain days but an AQI of 134 — the dust and haze the harmattan brings, layered on top of heat that doesn't let up for the season.

Forum posters describe Benin's coast as having two rainy seasons, April through July and September through mid-October, both generally recommended to avoid given unstable weather and a rougher sea. Posters instead point to late December through mid-February as the better overall window for a Cotonou visit. Given July falls within the first of those two rainy stretches, posters' framing implies hot, humid conditions with substantial rain and choppier coastal waters typical of this part of the West African coast. Posters generally rate July as one of Cotonou's weaker weather windows, with the December-February dry stretch a clearly better-regarded alternative.

Forum posters describe the Harmattan winds - dry Saharan air carrying a lot of dust - as a defining feature of this stretch of the West African coast from roughly late December through mid-February, meaning January sits squarely within that hazy, dust-laden but comparatively dry window. Posters specifically flag February through April as the hottest months of the year here, implying January itself, while still warm and humid on the coast, runs a touch more moderate than the peak heat still to come. Posters generally recommend light, breathable clothing regardless of the Harmattan's dry-air reputation, since the dust itself - rather than rain - is the main practical annoyance travelers report for a January visit to Cotonou.