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St Lucia weather in September 2025
Expect daytime maximum temperatures of 86°F in St Lucia in September and very high heat and humidity based on long-term weather averages. There are 8 hours of sunshine per day on average with 25 days with some rainfall and typically 8.8 inches of rainfall in the month.
- 86°F max day temperature
86 - 8 hours of sunshine per day
- 25 days with some rainfall
25 - 75°F min night temperature
75 - 12 hours of daylight per day
12 - Very High heat & humidity
VH - 8.8 inches of monthly rainfall
8.8 - 11+ (Extreme) UV index
11 - 84°F sea temperature
84
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Recommended for St Lucia
The September weather guide for St Lucia (Castries) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.
Top St Lucia destinations
Below are average maximum temperatures at popular countries, regions and places in St Lucia in September. Select a holiday destination to see more weather parameters.
All St Lucia destinations
- Anse la Raye
- Cap Estate
- Castries
- Choc Bay
- Grand Anse
- Gros Islet
- Marigot Bay
- Morgan Bay
- Reduit Beach
- Rodney Bay
- Soufriere
- Vieux Fort
Metric (°C) | Imperial (°F)
More about St Lucia
How hot is it in St Lucia in September?
Daytime temperatures usually reach 86°F in Castries, St Lucia in September with very high heat and humidity, falling to 75°F at night.
How sunny is it in St Lucia in September?
There are normally 8 hours of bright sunshine each day in Castries, St Lucia in September - that's 62% of daylight hours.
How warm is the sea around St Lucia in September?
The average sea temperature around Castries, St Lucia in September is 84°F.
Does it rain in St Lucia in September?
There are usually 25 days with some rain in Castries, St Lucia in September and the average monthly rainfall is 8.8 inches.
What is the chance of a hurricane in St Lucia in September?
On average 1.1 days in September in Castries, St Lucia are likely to be affected by the passage of one or more tropical storms.
St Lucia September sunrise & sunset times
Browse the sunrise and sunset times for St Lucia in September 2025. Select a month to view St Lucia sunrise and sunset times for the next 12 months. The St Lucia sunrise and sunset times shown below are for Castries.
JanFebMarAprMayJunJulAugSepOctNovDec
| Date | Sunrise times | Sunset times |
|---|---|---|
| Monday, 1st September 2025 | 05:52 | 18:15 |
| Monday, 15th September 2025 | 05:53 | 18:05 |
| Tuesday, 30th September 2025 | 05:54 | 17:54 |
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