Ontario, Canada · population 99,334 · 118 weather stations within 200 km · records 1819 to 2025
Thunder Bay has an average annual daytime high of 8.0°C, based on the 1951 to 1980 baseline. Its warmest month is July, when highs typically reach 23.9°C, and its coldest is January, with overnight lows near -20.8°C.
These figures reflect annual averages, not single-day records. Daily observations are outside this dataset's precision.
Since 1900, Thunder Bay's average temperature has risen by +2.5°C. Compared to the earliest station records that begin in 1819, warming totals +2.2°C.
20-year smoothed annual temperature reconstructed from station anomalies. Dashed line: 1951–1980 baseline.
Daytime highs sit within a comfortable 15°C to 26°C range.
Thunder Bay's average annual daytime high is 8.0°C, based on the 1951 to 1980 baseline period. The warmest month is July, with highs averaging 23.9°C, and the coldest is January, with lows averaging -20.8°C.
July is the warmest month in Thunder Bay, with typical daytime highs of 23.9°C.
2011 is the hottest year on record for Thunder Bay, running +3.2°C above the 1951 to 1980 baseline.
Yes. Since 1900, Thunder Bay has warmed by roughly +2.5°C.
May to September typically offers the most comfortable daytime highs, in the 15°C to 26°C range.
Baseline period 1951 to 1980. Monthly averages are the mean of station observations weighted by proximity. Warming trend is the 20-year smoothed anomaly against that baseline.