Climate averages 1991–2020
Thunder Bay weather
in April.
A cold, moderately wet month: the 7th warmest and the 6th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
April is a cold month in Thunder Bay: daytime highs average 5.1°C and nights cool to about -2.2°C. By daytime temperature it is the 7th warmest of the 12 months.
Expect about 54 mm of rain on roughly 8 days, which makes April a moderately wet month (the 6th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 38 min on an average April day.
The nearest other city in this atlas is Duluth (278 km away). In April its highs average 6.5°C, 1.4°C warmer than Thunder Bay, with 84 mm of rain.
Among the 86 cities listed in Canada, Thunder Bay ranks 85th of 86 for the warmest April highs and 15th of 86 for the driest April (rainfall, lowest first). The mean April high of those 86 cities is 10.3°C; Thunder Bay is 5.2°C cooler than that mean.
From April to May, average highs rise by 7.4°C to 12.5°C, and monthly rainfall rises from 54 mm to 66 mm.
The annual picture
April in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Thunder Bay climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -9.6°C-16.6°C | -16.6°C | 29 | 6.5 | 8.89 h |
| February | -8.0°C-15.0°C | -15.0°C | 22 | 4.9 | 10.210 h |
| March | -1.7°C-8.7°C | -8.7°C | 31 | 6.8 | 11.912 h |
| April, selected | 5.1°C-2.2°C | -2.2°C | 54 | 8.3 | 13.614 h |
| May | 12.5°C4.2°C | 4.2°C | 66 | 10.1 | 15.215 h |
| June | 18.3°C10.7°C | 10.7°C | 65 | 10.5 | 16.016 h |
| July | 22.3°C15.3°C | 15.3°C | 76 | 10.6 | 15.716 h |
| August | 22.3°C15.6°C | 15.6°C | 67 | 9.1 | 14.314 h |
| September | 17.8°C11.7°C | 11.7°C | 84 | 10.5 | 12.613 h |
| October | 9.9°C4.8°C | 4.8°C | 72 | 10.4 | 10.911 h |
| November | 2.3°C-2.8°C | -2.8°C | 49 | 7.8 | 9.39 h |
| December | -4.8°C-11.3°C | -11.3°C | 38 | 7.4 | 8.48 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
April in nearby cities
- Duluth in AprilUnited States · 278 kmHigh 6.5°C · Low -0.2°C · 84 mm rain
- Sault Ste. Marie in AprilCanada · 424 kmHigh 7.0°C · Low -1.4°C · 67 mm rain
- Green Bay in AprilUnited States · 440 kmHigh 11.3°C · Low 1.6°C · 80 mm rain
- Appleton in AprilUnited States · 463 kmHigh 11.4°C · Low 1.5°C · 81 mm rain
- Brooklyn Park in AprilUnited States · 481 kmHigh 12.4°C · Low 2.2°C · 81 mm rain
- Saint Paul in AprilUnited States · 482 kmHigh 12.6°C · Low 2.6°C · 81 mm rain
- Minneapolis in AprilUnited States · 487 kmHigh 12.5°C · Low 2.4°C · 81 mm rain
- Plymouth, United States in AprilUnited States · 493 kmHigh 12.3°C · Low 2.3°C · 81 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Thunder Bay) is explained once on the Thunder Bay year overview and on the Sources, method and limits page.