Guinea-Bissau weather by month

In Bissau, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.

The clearer part of the year begins around October 29 and lasts for 7.0 months, ending around May 29. The clearest month is March, when the sky is clear, mostly clear, or partly cloudy 83% of the time on average.

The cloudier part of the year begins around May 30 and lasts for 5.0 months, ending around October 28. The cloudiest month is August, when it is overcast or mostly cloudy 92% of the time.

This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.

Across the year, average wind speed in Bissau is typically calm, near 10 km/h, and varies moderately with the seasons.

The windier part of the year lasts 8.1 months, from around Dec 27 to Aug 29. The windiest month is May, averaging about 12 km/h (calm).

The calmer part of the year runs from around Aug 30 to Dec 26, with October the calmest month at about 7 km/h.

Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.

Bissau receives about 5.5 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 4.1 and 7.0 kWh/m².

The brighter stretch of the year lasts 5.0 months, from around Jan 11 to Jun 11. The brightest month is April, averaging about 7.0 kWh/m² (intense).

The dimmest month is August, down near 4.1 kWh/m² — roughly 41% less than the April peak.