The climate of Thunder Bay is influenced by Lake Superior, resulting in cooler summer temperatures and warmer winter temperatures. So when visiting, it’s important to pack for cooler weather and plan to wear layers that can easily accodate the temperature for that part of the day.

The average daily temperatures range from a high of 62 F/17.6 °C in July and a low of 5°F/-14.8 °C in January; the average daily high in July is 75°F/24.2 °C and the average daily high in January is 17°F/-8.6 °C. Summer daytime temperatures vary from 15° C to 30° C, while nights tend to be cooler and less humid than southern locations.

The summer period is well suited to both active and passive outdoor recreational pursuits. Recent winter daytime temperatures have ranged from springlike to relatively cold with sunny days. This type of climate is well suited to all kinds of active outdoor recreational pursuits. Spring and autumn are short with cool days and evenings.

Winter outdoor recreation often extends well into April while summer culminates in a spectacular show of colours in the fall.Precipitation is highly variable from year to year. The annual average rainfall is 527.3 mm while the average snowfall is 213 cm.
On average, Thunder Bay is the sunniest location in eastern, sunnier than any city in Canada located to the east of it.

Thunder Bay Weather Forecast

5 Day Weather Forecast

Thursday Thursday night Friday Showers High 17°C Showers High 17°C Showers High 12°C Saturday Sunday Monday Chance of showers High 11°C Sunny High 15°C Chance of showers High 16°C

Detailed Thunder Bay Weather Forecast

Thunder Bay Airport 06:00 AM EDT Thursday 15 May 2008

Thursday Increasing cloudiness. Showers beginning this afternoon. Risk of a thunderstorm. Fog patches dissipating early this morning. High 17. UV index 6 or high. Thursday night Showers ending late this evening then cloudy. Risk of a thunderstorm. Low minus 1. Friday Cloudy. Showers beginning in the morning and ending in the evening then 60 percent chance of showers later in the evening. Wind becoming northwest 20 km/h in the evening. High 12. Saturday Cloudy with 40 percent chance of showers. Low 6. High 11. Sunday Sunny. Low plus 3. High 15. Monday A mix of sun and cloud with 30 percent chance of showers. Low plus 5. High 16.