St Lucia weather in September
St Lucia averages 30°C by day and 26°C at night in September, with the sea at 30°C and 20 days with at least 1 mm of rain.
Day
30°C
Night
26°C
Sea
30°C
Rainy days
20
Flight from London
8½h
What September feels like
September is hot but wet in St Lucia: rainy season, so pack for showers.
The sea is warm at 30°C: comfortable for long swims.
It is rainy season, with rain on about 20 days.
Of the 48 sun destinations we track, St Lucia is the #15 warmest in September.
Want it warmer in September?
These are hotter than St Lucia this month for at most an hour and a half more flying:
St Lucia weather by month
September is highlighted. Compare with August and October, or see the full year in St Lucia.
St Lucia in September: quick answers
Is St Lucia hot in September?
September is hot but wet in St Lucia: rainy season, so pack for showers. Average highs are 30°C and lows 26°C.
Can you swim in St Lucia in September?
The sea is warm at 30°C: comfortable for long swims.
Does it rain in St Lucia in September?
It is rainy season, with rain on about 20 days.
What is the warmest month in St Lucia?
September, at an average high of 30°C. The coolest is January at 27°C.
How long is the flight to St Lucia from the UK?
About 8½h direct from London, estimated from the 6,769 km distance. Check your airline for exact times.
Still choosing? See where is hot in September for every destination ranked by temperature, sea and flight time.
How we measured this
Averages of every day in September from 2016 to 2025, from the Open-Meteo historical weather archive (ECMWF ERA5 reanalysis). Sea temperature is the 2023 to 2025 average from the Open-Meteo marine archive. A rainy day has at least 1 mm of rain. Reanalysis describes an area about 25 km across, so sheltered resorts can run a degree or two warmer. Flight time is a distance-based estimate from London Heathrow.
Planning St Lucia in September?
Save the restaurants, beaches and views you find on TikTok and Instagram for St Lucia straight to a map, then let Dream Trip turn them into a day-by-day plan.
