Key West weather in September 2025

Expect 31°C daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in Key West in September. Check more long-term weather averages for Key West in September before you book your next holiday to Florida in 2025/2026.

  • 31°C maximum daytime temperature in September in Key West31
    31°C max day temperature
  • 9 hours of sunshine per day
  • 15 days with some rainfall in September in Key West15
    15 days with some rainfall
  • 25°C minimum night-time temperature in September in Key West25
    25°C min night temperature
  • 12 hours of daylight per day in September in Key West12
    12 hours of daylight per day
  • Very high heat & humidity in September in Key WestVH
    Very High heat & humidity
  • 166 mm monthly rainfall in September in Key West166
    166 mm of monthly rainfall
  • UV (maximum) index 10 (Very High) in September in Key West10
    10 (Very High) UV index
  • 29°C sea temperature in September in Key West29
    29°C sea temperature

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The September weather guide for Florida (Key West) 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 Florida

How hot is it in Key West in September?

Daytime temperatures usually reach 31°C in Key West in September with very high heat and humidity, falling to 25°C at night.

How sunny is it in Key West in September?

There are normally 9 hours of bright sunshine each day in Key West in September - that's 73% of daylight hours.

How warm is the sea around Key West in September?

The average sea temperature around Key West in September is 29°C.

Does it rain in Key West in September?

There are usually 15 days with some rain in Key West in September and the average monthly rainfall is 166mm.

What is the chance of a hurricane in Key West in September?

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

Key West September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 06:08 18:45
Monday, 15th September 2025 06:13 18:31
Tuesday, 30th September 2025 06:19 18:15

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