Union Island weather in September 2025

Expect 30°C daytime maximum temperatures in the shade with on average 7 hours of sunshine per day in Union Island in September. Check more long-term weather averages for Union Island in September before you book your next holiday to St Vincent & the Grenadines in 2025/2026.

  • 30°C maximum daytime temperature in September in Union Island30
    30°C max day temperature
  • 7 hours of sunshine per day
  • 21 days with some rainfall in September in Union Island21
    21 days with some rainfall
  • 23°C minimum night-time temperature in September in Union Island23
    23°C min night temperature
  • 12 hours of daylight per day in September in Union Island12
    12 hours of daylight per day
  • Very high heat & humidity in September in Union IslandVH
    Very High heat & humidity
  • 186 mm monthly rainfall in September in Union Island186
    186 mm of monthly rainfall
  • UV (maximum) index 11+ (Extreme) in September in Union Island11
    11+ (Extreme) UV index
  • 29°C sea temperature in September in Union Island29
    29°C sea temperature

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The September weather guide for St Vincent & the Grenadines (Union Island) 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.

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

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More about St Vincent & the Grenadines

How hot is it in Union Island in September?

Daytime temperatures usually reach 30°C in Union Island in September with very high heat and humidity, falling to 23°C at night.

How sunny is it in Union Island in September?

There are normally 7 hours of bright sunshine each day in Union Island in September - that's 60% of daylight hours.

How warm is the sea around Union Island in September?

The average sea temperature around Union Island in September is 29°C.

Does it rain in Union Island in September?

There are usually 21 days with some rain in Union Island in September and the average monthly rainfall is 186mm.

What is the chance of a hurricane in Union Island in September?

On average less than 1 day in September in Union Island is likely to be affected by the passage of one or more tropical storms.

Union Island September sunrise & sunset times

Browse the sunrise and sunset times for Union Island in September 2025. Select a month to view Union Island sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:55 18:16
Monday, 15th September 2025 05:55 18:06
Tuesday, 30th September 2025 05:55 17:56

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