Cornwall Ont Hydro Weather Records (CA006101901)

Record envelope, standing records and threshold days for Cornwall Ont Hydro (CA006101901), Ontario, Canada, with 42 years of record.

Key Facts for Cornwall Ont Hydro

Cornwall Ont Hydro (CA006101901) is a weather station in Ontario, Canada at 45.03 latitude and -74.80 longitude, 76 m (249 ft) above sea level.
The station reports from 1954 to 1995, 42 years of record.
1,464 records set at Cornwall Ont Hydro still stand.
Records are tracked for no element yet: an element needs 30 years of data to be eligible.

About the Station

Location: Ontario, Canada, 45.03 latitude, -74.80 longitude.
Elevation: 76 m (249 ft).
Period of record: 1954 to 1995, 42 years.
Eligible elements: none yet.

Daily Record Envelope and 2026

0 days at or beyond a record

The band shows the record high and record low for each calendar day at Cornwall Ont Hydro. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.

Daily record high and record low at Cornwall Ont Hydro, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	13.9 C (57.0 F)	-38.9 C (-38.0 F)	n/a	n/a
Feb	14.5 C (58.1 F)	-33.3 C (-27.9 F)	n/a	n/a
Mar	24.4 C (75.9 F)	-27.0 C (-16.6 F)	n/a	n/a
Apr	28.3 C (82.9 F)	-14.4 C (6.1 F)	n/a	n/a
May	33.3 C (91.9 F)	-6.1 C (21.0 F)	n/a	n/a
Jun	36.1 C (97.0 F)	1.0 C (33.8 F)	n/a	n/a
Jul	35.6 C (96.1 F)	6.5 C (43.7 F)	n/a	n/a
Aug	36.1 C (97.0 F)	3.9 C (39.0 F)	n/a	n/a
Sep	32.5 C (90.5 F)	-2.8 C (27.0 F)	n/a	n/a
Oct	28.0 C (82.4 F)	-7.2 C (19.0 F)	n/a	n/a
Nov	23.3 C (73.9 F)	-17.0 C (1.4 F)	n/a	n/a
Dec	16.7 C (62.1 F)	-32.5 C (-26.5 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Cornwall Ont Hydro still stand. 1973 holds the most, with 71.

Standing records at Cornwall Ont Hydro by the year they were set
Year set	Standing records
1954	2
1955	70
1956	55
1957	63
1958	43
1959	69
1960	32
1961	31
1962	51
1963	64
1964	55
1965	58
1966	56
1967	63
1968	54
1969	39
1970	45
1971	28
1972	26
1973	71
1974	50
1975	39
1976	48
1977	45
1978	49
1979	50
1980	47
1981	69
1982	42
1983	50

Wettest Day of Each Month

Sep: 90.2 mm (3.6 in)

The wettest day on record for each calendar month at Cornwall Ont Hydro. The most was 90.2 mm (3.6 in) on 5 September 1973.

Record daily precipitation for each month at Cornwall Ont Hydro
Month	Record daily precipitation (mm)	Date
Jan	38.1 mm (1.5 in)	30 January 1966
Feb	40.6 mm (1.6 in)	13 February 1971
Mar	37.3 mm (1.5 in)	17 March 1973
Apr	50.8 mm (2.0 in)	3 April 1975
May	33.0 mm (1.3 in)	26 May 1956
Jun	62.0 mm (2.4 in)	23 June 1969
Jul	55.1 mm (2.2 in)	28 July 1966
Aug	70.6 mm (2.8 in)	18 August 1969
Sep	90.2 mm (3.6 in)	5 September 1973
Oct	48.3 mm (1.9 in)	9 October 1976
Nov	49.8 mm (2.0 in)	2 November 1967
Dec	56.7 mm (2.2 in)	12 December 1983

Period of Record Coverage

1954 to 1983

30 years of record at Cornwall Ont Hydro, 1954 to 1983. 4 years have data for under 90 percent of days and are left out of rankings: 1954, 1972, 1976, 1979.

Days with data per year at Cornwall Ont Hydro
Year	Days with data	Share of year	Complete
1954	30	8%	No
1955	365	100%	Yes
1956	366	100%	Yes
1957	335	92%	Yes
1958	348	95%	Yes
1959	365	100%	Yes
1960	366	100%	Yes
1961	365	100%	Yes
1962	364	100%	Yes
1963	363	99%	Yes
1964	365	100%	Yes
1965	365	100%	Yes
1966	365	100%	Yes
1967	365	100%	Yes
1968	366	100%	Yes
1969	365	100%	Yes
1970	365	100%	Yes
1971	332	91%	Yes
1972	244	67%	No
1973	365	100%	Yes
1974	365	100%	Yes
1975	334	92%	Yes
1976	274	75%	No
1977	334	92%	Yes
1978	365	100%	Yes
1979	275	75%	No
1980	365	100%	Yes
1981	364	100%	Yes
1982	333	91%	Yes
1983	363	99%	Yes

Latest Records

No records were set at this station in the latest data.

Climate Trend

20 complete years, 1955 to 1983

One stripe for each of 20 complete years at Cornwall Ont Hydro, 1955 to 1983. Blue stripes are years cooler than the station's own mean of 6.6 C (43.8 F); red stripes are warmer. The coolest year was 1978, at 5.7 C (42.2 F), and the warmest was 1973, at 7.6 C (45.6 F). The strongest colour marks a difference of 1.0 C (1.8 F).

Annual mean temperature at Cornwall Ont Hydro as warming stripes, 1955 to 1983
Year	Annual mean temperature	Difference from the station mean
1955	6.7 C	+0.12 C
1956	6.1 C	-0.43 C
1959	6.8 C	+0.24 C
1960	6.7 C	+0.16 C
1961	6.8 C	+0.29 C
1962	6.1 C	-0.48 C
1963	6.1 C	-0.48 C
1964	7.3 C	+0.71 C
1965	6.4 C	-0.12 C
1966	6.7 C	+0.19 C
1967	6.4 C	-0.15 C
1968	6.2 C	-0.33 C
1969	6.6 C	+0.06 C
1970	6.1 C	-0.47 C
1973	7.6 C	+1.00 C
1974	6.2 C	-0.31 C
1978	5.7 C	-0.86 C
1980	6.0 C	-0.55 C
1981	7.3 C	+0.73 C
1983	7.3 C	+0.75 C

This station does not have enough complete years (30 are needed) to fit a temperature trend.

A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.

Extremes by Year

1954 to 1983

Yearly extremes at Cornwall Ont Hydro: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	36.1 C (97.0 F)	1964	32.2 C (90.0 F)	30
Coldest night (TNn)	-38.9 C (-38.0 F)	1957	-30.3 C (-22.5 F)	30
Wettest day (Rx1day)	90.2 mm (3.6 in)	1973	48.2 mm (1.9 in)	29
Wettest five days (Rx5day)	136.5 mm (5.4 in)	1979	66.5 mm (2.6 in)	29
Longest dry spell (CDD)	44 days	1961	16 days	29

Hottest day (TXx)

The hottest day of the year at Cornwall Ont Hydro, 1954 to 1983. The record is 36.1 C (97.0 F) in 1964, marked on the chart; the median year is 32.2 C (90.0 F).

Hottest day (TXx) at Cornwall Ont Hydro by year
Year	Hottest day (TXx)
1954	3.9 C (39.0 F)
1955	35.6 C (96.1 F)
1956	32.2 C (90.0 F)
1957	33.3 C (91.9 F)
1958	32.2 C (90.0 F)
1959	33.3 C (91.9 F)
1960	31.7 C (89.1 F)
1961	30.6 C (87.1 F)
1962	33.3 C (91.9 F)
1963	33.9 C (93.0 F)
1964	36.1 C (97.0 F)
1965	32.2 C (90.0 F)
1966	33.3 C (91.9 F)
1967	31.1 C (88.0 F)
1968	32.8 C (91.0 F)
1969	32.2 C (90.0 F)
1970	31.7 C (89.1 F)
1971	31.7 C (89.1 F)
1972	28.3 C (82.9 F)
1973	32.8 C (91.0 F)
1974	31.1 C (88.0 F)
1975	36.1 C (97.0 F)
1976	30.0 C (86.0 F)
1977	31.5 C (88.7 F)
1978	33.0 C (91.4 F)
1979	34.0 C (93.2 F)
1980	32.0 C (89.6 F)
1981	34.0 C (93.2 F)
1982	32.0 C (89.6 F)
1983	33.5 C (92.3 F)

Coldest night (TNn)

The coldest night of the year at Cornwall Ont Hydro, 1954 to 1983. The record is -38.9 C (-38.0 F) in 1957, marked on the chart; the median year is -30.3 C (-22.5 F).

Coldest night (TNn) at Cornwall Ont Hydro by year
Year	Coldest night (TNn)
1954	-18.9 C (-2.0 F)
1955	-28.9 C (-20.0 F)
1956	-27.8 C (-18.0 F)
1957	-38.9 C (-38.0 F)
1958	-25.6 C (-14.1 F)
1959	-33.3 C (-27.9 F)
1960	-27.8 C (-18.0 F)
1961	-28.3 C (-18.9 F)
1962	-31.7 C (-25.1 F)
1963	-29.4 C (-20.9 F)
1964	-28.9 C (-20.0 F)
1965	-29.4 C (-20.9 F)
1966	-32.2 C (-26.0 F)
1967	-30.6 C (-23.1 F)
1968	-32.8 C (-27.0 F)
1969	-25.6 C (-14.1 F)
1970	-30.6 C (-23.1 F)
1971	-31.7 C (-25.1 F)
1972	-33.3 C (-27.9 F)
1973	-31.1 C (-24.0 F)
1974	-31.1 C (-24.0 F)
1975	-31.1 C (-24.0 F)
1976	-32.8 C (-27.0 F)
1977	-28.9 C (-20.0 F)
1978	-30.0 C (-22.0 F)
1979	-28.0 C (-18.4 F)
1980	-32.5 C (-26.5 F)
1981	-35.0 C (-31.0 F)
1982	-28.5 C (-19.3 F)
1983	-28.0 C (-18.4 F)

Wettest day (Rx1day)

The wettest day of the year at Cornwall Ont Hydro, 1954 to 1983. The record is 90.2 mm (3.6 in) in 1973, marked on the chart; the median year is 48.2 mm (1.9 in).

Wettest day (Rx1day) at Cornwall Ont Hydro by year
Year	Wettest day (Rx1day)
1954	n/a
1955	54.4 mm (2.1 in)
1956	33.0 mm (1.3 in)
1957	31.8 mm (1.3 in)
1958	26.2 mm (1.0 in)
1959	39.6 mm (1.6 in)
1960	37.3 mm (1.5 in)
1961	38.4 mm (1.5 in)
1962	55.9 mm (2.2 in)
1963	55.9 mm (2.2 in)
1964	34.8 mm (1.4 in)
1965	69.6 mm (2.7 in)
1966	55.1 mm (2.2 in)
1967	49.8 mm (2.0 in)
1968	38.4 mm (1.5 in)
1969	70.6 mm (2.8 in)
1970	34.3 mm (1.4 in)
1971	41.1 mm (1.6 in)
1972	40.9 mm (1.6 in)
1973	90.2 mm (3.6 in)
1974	48.3 mm (1.9 in)
1975	63.5 mm (2.5 in)
1976	51.6 mm (2.0 in)
1977	36.2 mm (1.4 in)
1978	38.1 mm (1.5 in)
1979	71.3 mm (2.8 in)
1980	27.5 mm (1.1 in)
1981	48.2 mm (1.9 in)
1982	68.6 mm (2.7 in)
1983	56.7 mm (2.2 in)

Wettest five days (Rx5day)

The wettest five days of the year at Cornwall Ont Hydro, 1954 to 1983. The record is 136.5 mm (5.4 in) in 1979, marked on the chart; the median year is 66.5 mm (2.6 in).

Wettest five days (Rx5day) at Cornwall Ont Hydro by year
Year	Wettest five days (Rx5day)
1954	n/a
1955	91.5 mm (3.6 in)
1956	62.0 mm (2.4 in)
1957	49.0 mm (1.9 in)
1958	61.0 mm (2.4 in)
1959	66.5 mm (2.6 in)
1960	66.0 mm (2.6 in)
1961	76.7 mm (3.0 in)
1962	72.5 mm (2.9 in)
1963	66.8 mm (2.6 in)
1964	46.0 mm (1.8 in)
1965	79.3 mm (3.1 in)
1966	60.9 mm (2.4 in)
1967	53.1 mm (2.1 in)
1968	59.1 mm (2.3 in)
1969	117.1 mm (4.6 in)
1970	60.5 mm (2.4 in)
1971	63.5 mm (2.5 in)
1972	50.8 mm (2.0 in)
1973	126.3 mm (5.0 in)
1974	59.2 mm (2.3 in)
1975	83.3 mm (3.3 in)
1976	75.3 mm (3.0 in)
1977	68.0 mm (2.7 in)
1978	51.1 mm (2.0 in)
1979	136.5 mm (5.4 in)
1980	60.7 mm (2.4 in)
1981	76.0 mm (3.0 in)
1982	89.4 mm (3.5 in)
1983	78.7 mm (3.1 in)

Longest dry spell (CDD)

The longest dry spell of the year at Cornwall Ont Hydro, 1954 to 1983. The record is 44 days in 1961, marked on the chart; the median year is 16 days.

Longest dry spell (CDD) at Cornwall Ont Hydro by year
Year	Longest dry spell (CDD)
1954	n/a
1955	15 days
1956	15 days
1957	23 days
1958	9 days
1959	16 days
1960	19 days
1961	44 days
1962	13 days
1963	19 days
1964	15 days
1965	19 days
1966	13 days
1967	17 days
1968	13 days
1969	19 days
1970	18 days
1971	19 days
1972	20 days
1973	14 days
1974	12 days
1975	17 days
1976	11 days
1977	14 days
1978	16 days
1979	9 days
1980	19 days
1981	10 days
1982	17 days
1983	10 days

Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.

Frost Dates and Growing Season

20 years with a frost

Across 20 years with a frost, the median last spring frost at Cornwall Ont Hydro falls on 11 May and the median first autumn frost on 4 October, which leaves a median of 149 days between them.

Frost dates and growing season at Cornwall Ont Hydro
Measure	Median, all years	Earliest period	Recent period (1955 to 1983)	Recent against earliest	Fitted trend
Last spring frost	11 May	n/a	11 May	n/a	n/a
First autumn frost	4 October	n/a	4 October	n/a	n/a
Growing days	149 days	n/a	149 days	n/a	n/a

A frost day is a day with a daily minimum at or below 0 C (32 F). The last spring frost and the first autumn frost are the last and first such days of the cold season, and growing days are the days between them. A negative trend for the last spring frost means it comes earlier.

Download the Data

Data for Cornwall Ont Hydro standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Cornwall Ont Hydro threshold days by year: CSV or JSON. Field meanings are on the data page.

Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-14 (14 October 2026). Records are computed by this site and are not official.

Data as of 2026-10-14. Last revised 14 October 2026 (2026-10-14).