British Indian Ocean Territory weather in September 2025

Expect 29°C daytime maximum temperatures in the shade with on average -9999 hours of sunshine per day in British Indian Ocean Territory in September. Check more long-term weather averages for British Indian Ocean Territory in September before you book your next holiday to British Indian Ocean Territory in 2025/2026.

  • 29°C maximum daytime temperature in September in British Indian Ocean Territory (Diego Garcia)29
    29°C max day temperature
  • 16 days with some rainfall in September in British Indian Ocean Territory (Diego Garcia)16
    16 days with some rainfall
  • 24°C minimum night-time temperature in September in British Indian Ocean Territory (Diego Garcia)24
    24°C min night temperature
  • 12 hours of daylight per day in September in British Indian Ocean Territory (Diego Garcia)12
    12 hours of daylight per day
  • High heat & humidity in September in British Indian Ocean Territory (Diego Garcia)H
    High heat & humidity
  • 228 mm monthly rainfall in September in British Indian Ocean Territory (Diego Garcia)228
    228 mm of monthly rainfall
  • UV (maximum) index 11+ (Extreme) in September in British Indian Ocean Territory (Diego Garcia)11
    11+ (Extreme) UV index
  • 27°C sea temperature in September in British Indian Ocean Territory (Diego Garcia)27
    27°C sea temperature

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The September weather guide for British Indian Ocean Territory, represented by Diego Garcia, (Diego Garcia) 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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How hot is it in the British Indian Ocean Territory in September?

Daytime temperatures usually reach 29°C in Diego Garcia, British Indian Ocean Territory in September with high heat and humidity, falling to 24°C at night.

How warm is the sea around the British Indian Ocean Territory in September?

The average sea temperature around Diego Garcia, British Indian Ocean Territory in September is 27°C.

Does it rain in the British Indian Ocean Territory in September?

There are usually 16 days with some rain in Diego Garcia, British Indian Ocean Territory in September and the average monthly rainfall is 228mm.

What is the chance of a cyclone in the British Indian Ocean Territory in September?

On average less than 1 day in September in Diego Garcia, British Indian Ocean Territory is likely to be affected by the passage of one or more tropical storms.

British Indian Ocean Territory September sunrise & sunset times

Browse the sunrise and sunset times for British Indian Ocean Territory in September 2025. Select a month to view British Indian Ocean Territory sunrise and sunset times for the next 12 months. The British Indian Ocean Territory sunrise and sunset times shown below are for Diego Garcia.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 07:11 19:10
Monday, 15th September 2025 07:04 19:07
Tuesday, 30th September 2025 06:56 19:05

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