Earliest and Latest Days of 30° C in Cornwall

This is a list of the earliest and latest days in the year with a high temperature of at least 30 °C in Cornwall, Ontario history. It is based on NOAA data from the years 1867–2024.

Also see:

Earliest 30 degree day in Cornwall?

The earliest in the year that Cornwall, Ontario had a high temperature of at least 30 °C is April 14 which happened in 1869.

Latest 30 degree day in Cornwall?

The latest in the year that Cornwall, Ontario had a high temperature of at least 30 °C is October 5 which happened in 2023.

Earliest Days ≥ 30 °C

Date	Year	Temperature
April 14	1869	30.0 °C
April 27	2009	31.0 °C
April 27	1990	30.5 °C
May 3	2001	30.0 °C
May 7	1982	30.0 °C
May 8	2015	30.0 °C
May 9	2015	30.0 °C
May 9	1880	30.0 °C
May 10	1887	30.6 °C
May 12	2022	31.5 °C
May 13	2022	30.0 °C
May 14	2022	31.5 °C
May 15	2014	32.0 °C
May 15	1961	31.1 °C
May 16	1998	31.5 °C
May 16	1991	30.5 °C
May 17	2017	30.0 °C
May 17	1977	30.0 °C
May 17	1962	30.6 °C
May 18	2017	30.0 °C
May 18	2015	30.5 °C
May 18	1999	31.0 °C
May 18	1989	30.5 °C
May 18	1962	32.2 °C

Latest Days ≥ 30 °C

Date	Year	Temperature
October 5	2023	30.0 °C
October 4	2023	31.5 °C
September 30	1881	30.0 °C
September 27	2017	31.0 °C
September 26	2017	30.0 °C
September 25	2017	32.5 °C
September 25	2007	30.5 °C
September 24	2017	31.0 °C
September 23	2017	31.0 °C
September 22	1965	31.7 °C
September 20	1983	31.0 °C
September 20	1867	30.0 °C
September 19	1955	30.0 °C
September 18	2015	30.0 °C
September 17	2018	30.0 °C
September 16	2018	30.0 °C
September 16	1991	30.0 °C
September 15	2018	32.0 °C
September 15	1877	31.7 °C
September 14	2018	30.0 °C
September 14	2003	30.0 °C
September 14	1993	30.0 °C
September 14	1951	31.1 °C