Fogo has a dry season (December to July) and a rainy season (August to November). The dry months are the best time to climb Pico do Fogo — cloud cover is lower and visibility from the summit is better. The rainy season brings humidity to the lower elevations but can make the caldera area foggy and the summit obscured for days at a time.
November to February can be cool at altitude — Chã das Caldeiras sits at 1,700 metres and temperatures at night can drop to single digits. The summit is colder still. Bring warm layers for any stay in the caldera.
Avoid planning a summit climb on a day with overcast skies — the view from the top is the reward, and cloud cover can eliminate it entirely.