Reunion weather by month

In Saint-Denis, 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 April 16 and lasts for 5.9 months, ending around October 13. The clearest month is July, when the sky is clear, mostly clear, or partly cloudy 84% of the time on average.

The cloudier part of the year begins around October 14 and lasts for 6.0 months, ending around April 15. The cloudiest month is January, when it is overcast or mostly cloudy 64% 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.

Wind in Saint-Denis is steady company: average speeds sit near 8 km/h — calm — in every month of the year, with no meaningful windy or calm season.

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.

Saint-Denis receives about 5.7 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.9 and 7.2 kWh/m².

The brighter stretch of the year lasts 6.6 months, from around Sep 10 to Mar 28. The brightest month is December, averaging about 7.1 kWh/m² (intense).

The dimmest month is June, down near 4.0 kWh/m² — roughly 44% less than the December peak.