Last updated: June 18, 2025
In May, the average temperature in Thunder Bay, Canada hovers around 8°C (47°F). During this month, temperatures can range from a chilly -5°C (23°F) to a pleasant 24°C (76°F). Expect 52 mm (2.0 in) of precipitation over approximately 9 days, coupled with an average humidity level of 78%, creating a damp but invigorating atmosphere.
In May in Thunder Bay, the average temperature is 8°C (47°F). Maximum temperatures can reach up to 24°C (76°F), while the minimum can drop as low as -5°C (23°F). It's advisable to pack layers to accommodate the varying temperatures during your travels.
In Thunder Bay in May, the precipitation amount is 52 mm (2.0 in) over a span of 9 days.
In Thunder Bay in May, humidity is 78%. With an average temperature of 8°C (47°F), this humidity feels like a chilly embrace, making travel invigorating yet damp, as the cool air wraps around you, emphasizing the need for layers to stay comfortable while exploring.
In Thunder Bay in May, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Thunder Bay.
UV Risk Categories
Weather in Thunder Bay varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Thunder Bay, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -13°C (9°F) | 30 mm (1.2 inches) | 95% | low |
| February Weather | -13°C (9°F) | 35 mm (1.4 inches) | 94% | moderate |
| March Weather | -5°C (23°F) | 31 mm (1.2 inches) | 92% | moderate |
| April Weather | 1°C (33°F) | 58 mm (2.3 inches) | 90% | high |
| May Weather | 8°C (47°F) | 52 mm (2.0 inches) | 78% | very high |
| June Weather | 14°C (58°F) | 58 mm (2.3 inches) | 71% | very high |
| July Weather | 19°C (66°F) | 82 mm (3.2 inches) | 70% | very high |
| August Weather | 17°C (63°F) | 77 mm (3.0 inches) | 72% | very high |
| September Weather | 13°C (55°F) | 98 mm (3.9 inches) | 76% | high |
| October Weather | 6°C (43°F) | 87 mm (3.4 inches) | 82% | moderate |
| November Weather | -3°C (27°F) | 51 mm (2.0 inches) | 87% | low |
| December Weather | -9°C (16°F) | 55 mm (2.2 inches) | 94% | low |