Thunder Bay weather in September 2026

Expect daytime maximum temperatures of 63°F in Thunder Bay, Ontario in September based on long-term weather averages. There are 5 hours of sunshine per day on average with 13 days with some rainfall and typically 3.5 inches of rainfall in the month.

  • 63°F maximum daytime temperature in September in Thunder Bay63
    63°F max day temperature
  • 5 hours of sunshine per day
  • 13 days with some rainfall in September in Thunder Bay13
    13 days with some rainfall
  • 43°F minimum night-time temperature in September in Thunder Bay43
    43°F min night temperature
  • 13 hours of daylight per day in September in Thunder Bay13
    13 hours of daylight per day
  • No heat & humidity in September in Thunder Bay0
    No heat & humidity
  • 3.5 inches monthly rainfall in September in Thunder Bay3.5
    3.5 inches of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Thunder Bay5
    5 (Moderate) UV index
  • 55°F sea temperature in September in Thunder Bay55
    55°F sea temperature

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The September weather guide for Ontario (Thunder Bay) 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)  |  Imperial (°F)

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More about Ontario

How hot is it in Thunder Bay in September?

Daytime temperatures usually reach 70°F in Thunder Bay in September, falling to 52°F at night.

How sunny is it in Thunder Bay in September?

There are normally 6 hours of bright sunshine each day in Thunder Bay in September - that's 48% of daylight hours.

How warm is the sea around Thunder Bay in September?

The average sea temperature around Thunder Bay in September is 66°F.

Does it rain in Thunder Bay in September?

There are usually 10 days with some rain in Thunder Bay in September and the average monthly rainfall is 3.0 inches.

Thunder Bay September sunrise & sunset times

Browse the sunrise and sunset times for Thunder Bay in September 2026. Select a month to view Thunder Bay sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Tuesday, 1st September 2026 06:14 19:38
Tuesday, 15th September 2026 06:34 19:09
Wednesday, 30th September 2026 06:55 18:38

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