The five months I’d pick first
November and February tie for best all-round. Dry, warm, low humidity, blue skies, moderate prices, everything open, no crowds. If you can only visit once, pick either. Late October is nearly as good, and the first week of August (the August Break) is a sleeper choice — cool, dry, and priced like low season. December is the fifth pick if you want energy and nightlife and don’t mind paying triple. Every other month has a serious downside.
January is fine but harmattan dust bothers some visitors. March is hot and humid. April is decent until the last week. May through July is rainy season, cheap but limited. September is the flood month. October is transitional and unreliable until mid-month.
By travel purpose
Beach and outdoor priority: November, February, August Break, late October. Nightlife and events: December, first two weeks of January, late November. Business trips with tight budgets: May, June, July, September — rates 40-50% below peak and meetings actually happen quickly because the city is quieter. Family trips with kids: February and November are safest for consistent weather. Photography and wildlife at the Lekki Conservation Centre: August and November when the vegetation is green but paths are dry.
Avoid if possible: mid-May through late June (heaviest storms and expressway flooding), September (worst floods), and December 20-31 unless you’re specifically coming for the parties and have booked months ahead.
Good to know
What's the single best week?+
The first week of February. Dry, uncrowded, post-Detty-December pricing, harmattan fading.
What's the worst week?+
The third week of September in a heavy-rain year. Flooding can shut expressways for hours.