Ontario weather in September 2025

Expect 21°C daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in Ontario in September. Check more long-term weather averages for Ontario in September before you book your next holiday to Ontario in 2025/2026.

  • 21°C maximum daytime temperature in September in Ontario (Toronto)21
    21°C max day temperature
  • 6 hours of sunshine per day
  • 10 days with some rainfall in September in Ontario (Toronto)10
    10 days with some rainfall
  • 11°C minimum night-time temperature in September in Ontario (Toronto)11
    11°C min night temperature
  • 12 hours of daylight per day in September in Ontario (Toronto)12
    12 hours of daylight per day
  • No heat & humidity in September in Ontario (Toronto)0
    No heat & humidity
  • 75 mm monthly rainfall in September in Ontario (Toronto)75
    75 mm of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Ontario (Toronto)5
    5 (Moderate) UV index
  • 19°C sea temperature in September in Ontario (Toronto)19
    19°C sea temperature

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The September weather guide for Ontario (Toronto) 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.

Top Ontario destinations

Below are average maximum temperatures at popular countries, regions and places in Ontario in September. Select a holiday destination to see more weather parameters.

All Ontario destinations

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

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More about Canada

How hot is it in Ontario in September?

Daytime temperatures usually reach 21°C in Toronto, Ontario in September, falling to 11°C at night.

How sunny is it in Ontario in September?

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

How warm is the sea around Ontario in September?

The average sea temperature around Toronto, Ontario in September is 19°C.

Does it rain in Ontario in September?

There are usually 10 days with some rain in Toronto, Ontario in September and the average monthly rainfall is 75mm.

Ontario September sunrise & sunset times

Browse the sunrise and sunset times for Ontario in September 2025. Select a month to view Ontario sunrise and sunset times for the next 12 months. The Ontario sunrise and sunset times shown below are for Toronto.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:42 18:53
Monday, 15th September 2025 05:57 18:27
Tuesday, 30th September 2025 06:14 18:00

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