Helsinki weather in September 2025

Expect daytime maximum temperatures of 14°C in Helsinki, Finland in September based on long-term weather averages. There are 4 hours of sunshine per day on average with 17 days with some rainfall and typically 73 mm of rainfall in the month.

  • 14°C maximum daytime temperature in September in Helsinki14
    14°C max day temperature
  • 4 hours of sunshine per day
  • 17 days with some rainfall in September in Helsinki17
    17 days with some rainfall
  • 7°C minimum night-time temperature in September in Helsinki7
    7°C min night temperature
  • 13 hours of daylight per day in September in Helsinki13
    13 hours of daylight per day
  • No heat & humidity in September in Helsinki0
    No heat & humidity
  • 73 mm monthly rainfall in September in Helsinki73
    73 mm of monthly rainfall
  • UV (maximum) index 3 (Moderate) in September in Helsinki3
    3 (Moderate) UV index
  • 14°C sea temperature in September in Helsinki14
    14°C sea temperature

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The September weather guide for Finland (Helsinki) 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 warm is it in Helsinki in September?

Daytime temperatures usually reach 14°C in Helsinki in September, falling to 7°C at night.

How sunny is it in Helsinki in September?

There are normally 4 hours of bright sunshine each day in Helsinki in September - that's 33% of daylight hours.

How warm is the sea around Helsinki in September?

The average sea temperature around Helsinki in September is 14°C.

Does it rain in Helsinki in September?

There are usually 17 days with some rain in Helsinki in September and the average monthly rainfall is 73mm.

Helsinki September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:15 19:24
Monday, 15th September 2025 05:48 18:41
Tuesday, 30th September 2025 06:24 17:55

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