The highest day temperature in April 2025 was 52°F. The lowest night temperature was 13°F. The average values for day and night temperatures during April were 38.0°F и 29.1°F respectivly.

The average sea surface temperature in April 2025 for Thunder Bay was 32.7°F. The maximum and minimum values were 30.8°F and 37.2°F respectively.

Most of the days in April are gloomy but you can also expect sunny days.

Precipitation total in April for Thunder Bay is 1.1 in. It makes april the most rainy month of the year.

The average wind speed in April is 8.8 mph. It makes April one of the most windy months 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 April is 4.5 hours.