Thunder Bay weather in May 2025

Expect 59°F daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Thunder Bay in May. Check more long-term weather averages for Thunder Bay in May before you book your next holiday to Ontario in 2025/2026.

  • 59°F maximum daytime temperature in May in Thunder Bay59
    59°F max day temperature
  • 8 hours of sunshine per day
  • 11 days with some rainfall in May in Thunder Bay11
    11 days with some rainfall
  • 36°F minimum night-time temperature in May in Thunder Bay36
    36°F min night temperature
  • 15 hours of daylight per day in May in Thunder Bay15
    15 hours of daylight per day
  • No heat & humidity in May in Thunder Bay0
    No heat & humidity
  • 2.8 inches monthly rainfall in May in Thunder Bay2.8
    2.8 inches of monthly rainfall
  • UV (maximum) index 6 (High) in May in Thunder Bay6
    6 (High) UV index
  • 37°F sea temperature in May in Thunder Bay37
    37°F sea temperature

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The May 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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How warm is it in Thunder Bay in May?

Daytime temperatures usually reach 59°F in Thunder Bay in May, falling to 36°F at night.

How sunny is it in Thunder Bay in May?

There are normally 8 hours of bright sunshine each day in Thunder Bay in May - that's 55% of daylight hours.

How warm is the sea around Thunder Bay in May?

The average sea temperature around Thunder Bay in May is 37°F.

Does it rain in Thunder Bay in May?

There are usually 11 days with some rain in Thunder Bay in May and the average monthly rainfall is 2.8 inches.

Thunder Bay May sunrise & sunset times

Browse the sunrise and sunset times for Thunder Bay in May 2025. Select a month to view Thunder Bay sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Thursday, 1st May 2025 05:37 20:12
Friday, 16th May 2025 05:15 20:33
Saturday, 31st May 2025 05:00 20:50

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