Earliest and Latest Days of 30° C in Thunder Bay

This is a list of the earliest and latest days in the year with a high temperature of at least 30 °C in Thunder Bay, Ontario history. It is based on NOAA data from the years 1941–2024.

Also see:

Earliest 30 degree day in Thunder Bay?

The earliest in the year that Thunder Bay, Ontario had a high temperature of at least 30 °C is May 4 which happened in 1980.

Latest 30 degree day in Thunder Bay?

The latest in the year that Thunder Bay, Ontario had a high temperature of at least 30 °C is October 2 which happened in 2023.

Earliest Days ≥ 30 °C

Date	Year	Temperature
May 4	1980	32.6 °C
May 7	1953	30.6 °C
May 8	1953	32.8 °C
May 9	1985	30.0 °C
May 11	1991	30.3 °C
May 12	1977	33.0 °C
May 15	1991	31.9 °C
May 16	1977	30.1 °C
May 17	1962	30.0 °C
May 18	1984	30.5 °C
May 18	1978	30.5 °C
May 19	1972	30.6 °C
May 20	1992	31.2 °C
May 20	1980	30.1 °C
May 21	1980	32.5 °C
May 22	1980	34.8 °C
May 25	2014	30.9 °C
May 26	1948	31.7 °C
May 27	1986	30.6 °C
May 28	1986	33.0 °C
May 28	1969	33.9 °C
May 28	1944	30.0 °C

Latest Days ≥ 30 °C

Date	Year	Temperature
October 2	2023	30.0 °C
September 18	1976	30.6 °C
September 12	2002	30.0 °C
September 11	2011	30.1 °C
September 11	2005	34.1 °C
September 11	1998	32.0 °C
September 11	1976	31.7 °C
September 9	2011	30.7 °C
September 8	2011	30.6 °C
September 8	2002	31.3 °C
September 7	1959	30.0 °C
September 6	2015	30.5 °C
September 6	1945	30.6 °C
September 5	2023	30.8 °C
September 5	1998	33.1 °C
September 3	2023	32.8 °C
September 3	1955	30.0 °C
September 2	2023	32.6 °C
September 2	1983	31.4 °C
September 2	1971	30.6 °C