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Cornwall September Weather

Averages and records for weather in Cornwall, Ontario in the month of September.

Typical Cornwall September Weather 1991–2020
Average daily high	21.9 °C
Average daily low	11.7 °C
Average monthly precipitation	9.4 cm
Average monthly snow	none
Daily chance of precipitation	37.2%
Daily chance of snow	0%

Cornwall September Weather Records 1867–2024
Highest temperature	34.5 °C	September 9, 2002
Lowest temperature	-6.1 °C	September 30, 1951
Highest daily low	24.5 °C	September 8, 2007
Lowest daily high	7.0 °C	September 30, 1992
Hottest average high temperature	24.8 °C	2002
Coldest average high temperature	18.0 °C	1981
Most daily precipitation	11.0 cm	September 14, 1979
Most monthly precipitation	19.8 cm	2010
Most daily snow	none	-
Most monthly snow	none	-

Note: Daily averages are a moving average which includes 14 days before and after

Day	Average (°C)		Record (°C)
Day	High	Low	High	Low
September 1	24.4	14.3	32.2	3.9
September 2	24.2	14.1	32.2	3.9
September 3	24.1	14.0	33.0	3.9
September 4	24.0	13.8	34.5	3.3
September 5	23.9	13.6	34.0	3.9
September 6	23.7	13.5	33.0	3.9
September 7	23.6	13.3	33.0	0.6
September 8	23.5	13.2	33.5	-1.1
September 9	23.2	13.1	34.5	0.0
September 10	23.0	12.8	33.0	0.6
September 11	22.8	12.6	31.0	0.0
September 12	22.7	12.4	29.4	2.2
September 13	22.5	12.3	31.1	1.1
September 14	22.4	12.1	31.1	-1.7
September 15	22.1	11.9	32.0	-0.6
September 16	21.8	11.7	30.0	-2.8
September 17	21.6	11.5	30.0	-0.6
September 18	21.3	11.3	30.0	-1.7
September 19	21.1	11.1	30.0	-1.0
September 20	20.8	11.0	31.0	1.1
September 21	20.6	10.7	29.4	-1.1
September 22	20.3	10.5	31.7	-1.1
September 23	20.1	10.2	31.0	-3.9
September 24	19.9	10.0	31.0	-3.3
September 25	19.6	9.9	32.5	-1.1
September 26	19.4	9.7	30.0	-0.6
September 27	19.2	9.5	31.0	-1.1
September 28	19.0	9.3	29.4	-4.4
September 29	18.8	9.0	28.9	-2.8
September 30	18.5	8.8	30.0	-6.1

Weather Station Details

Years	Station	Coordinates
1950–2024	Cornwall	location
1867–1887	Cornwall	location