The highest day temperature in July 2025 was 85°F. The lowest night temperature was 49°F. The average values for day and night temperatures during July were 71.8°F и 57.7°F respectivly.

The average sea surface temperature in July 2025 for Thunder Bay was 62.4°F. The maximum and minimum values were 55.8°F and 66.6°F respectively.

You can expect various weather conditions during July. Be ready for sunny, cloudy or even gloomy days.

Precipitation total in July for Thunder Bay is 0.8 in. It makes july one of the most rainy months of the year.

The average wind speed in July is 5.8 mph. It makes July the most windless month of the year for Thunder Bay.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Thunder Bay in July is 9.3 hours.