St Lucia weather in September 2025

Expect 30°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in St Lucia in September. Check more long-term weather averages for St Lucia in September before you book your next holiday to St Lucia in 2025/2026.

  • 30°C maximum daytime temperature in September in St Lucia (Castries)30
    30°C max day temperature
  • 8 hours of sunshine per day
  • 25 days with some rainfall in September in St Lucia (Castries)25
    25 days with some rainfall
  • 24°C minimum night-time temperature in September in St Lucia (Castries)24
    24°C min night temperature
  • 12 hours of daylight per day in September in St Lucia (Castries)12
    12 hours of daylight per day
  • Very high heat & humidity in September in St Lucia (Castries)VH
    Very High heat & humidity
  • 224 mm monthly rainfall in September in St Lucia (Castries)224
    224 mm of monthly rainfall
  • UV (maximum) index 11+ (Extreme) in September in St Lucia (Castries)11
    11+ (Extreme) UV index
  • 29°C sea temperature in September in St Lucia (Castries)29
    29°C sea temperature

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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.

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Metric (°C / mm)  |  Imperial (°F / inches)

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More about St Lucia

How hot is it in St Lucia in September?

Daytime temperatures usually reach 30°C in Castries, St Lucia in September with very high heat and humidity, falling to 24°C 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 29°C.

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 224mm.

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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