Saint Lucia weather by month

In Gros Islet, 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 November 21 and lasts for 4.5 months, ending around April 5. The clearest month is January, when the sky is clear, mostly clear, or partly cloudy 87% of the time on average.

The cloudier part of the year begins around July 27 and lasts for 3.8 months, ending around November 20. The cloudiest month is September, when it is overcast or mostly cloudy 55% 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 Gros Islet is typically light breeze, near 20 km/h, and varies moderately with the seasons.

The windier part of the year lasts 7.7 months, from around Dec 8 to Jul 29. The windiest month is June, averaging about 22 km/h (breezy).

The calmer part of the year runs from around Jul 30 to Dec 7, with September the calmest month at about 16 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.

Gros Islet receives about 5.9 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 4.9 and 6.7 kWh/m².

The brighter stretch of the year lasts 7.0 months, from around Feb 18 to Sep 17. The brightest month is April, averaging about 6.6 kWh/m² (intense).

The dimmest month is December, down near 4.9 kWh/m² — roughly 25% less than the April peak.