Most Monthly Precipitation in Thunder Bay History

This is a list of the largest monthly precipitation totals ever recorded in Thunder Bay, Ontario history from 1941–2024.

What Was the Wettest Month in Thunder Bay History?

According to NOAA records, the most precipitation that Thunder Bay, Ontario has ever received in a single month is 28.4 cm which occurred in September 1977.

Thunder Bay Most Rain in One Month

Rank	Precipitation	Month
1	28.4 cm	September 1977
2	21.3 cm	June 2016
3	21.2 cm	September 1941
4	20.3 cm	July 1993
5	20.0 cm	July 1982
6	19.4 cm	June 2008
7	19.2 cm	May 2012
8	18.8 cm	April 2001
9	18.3 cm	April 2022
10	18.1 cm	June 1944
11	17.5 cm	September 1980
12	17.4 cm	May 1971
13	17.0 cm	August 1988
14	17.0 cm	June 1981
15	16.9 cm	July 1968
16	16.9 cm	August 1977
17	16.7 cm	October 1970
18	16.6 cm	September 1965
19	16.6 cm	June 1947
20	16.6 cm	August 1944