Chalk River Aecl Weather Records (CA006101335)

Record envelope, standing records and threshold days for Chalk River Aecl (CA006101335), Ontario, Canada, with 65 years of record.

Key Facts for Chalk River Aecl

Chalk River Aecl (CA006101335) is a weather station in Ontario, Canada at 46.05 latitude and -77.37 longitude, 122 m (400 ft) above sea level.
The station reports from 1960 to 2024, 65 years of record.
1,464 records set at Chalk River Aecl 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, 46.05 latitude, -77.37 longitude.
Elevation: 122 m (400 ft).
Period of record: 1960 to 2024, 65 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 Chalk River Aecl. 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 Chalk River Aecl, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	11.1 C (52.0 F)	-39.0 C (-38.2 F)	n/a	n/a
Feb	12.0 C (53.6 F)	-35.6 C (-32.1 F)	n/a	n/a
Mar	23.9 C (75.0 F)	-32.0 C (-25.6 F)	n/a	n/a
Apr	31.7 C (89.1 F)	-19.4 C (-2.9 F)	n/a	n/a
May	34.0 C (93.2 F)	-8.9 C (16.0 F)	n/a	n/a
Jun	35.0 C (95.0 F)	-1.7 C (28.9 F)	n/a	n/a
Jul	39.4 C (102.9 F)	3.3 C (37.9 F)	n/a	n/a
Aug	37.2 C (99.0 F)	-3.0 C (26.6 F)	n/a	n/a
Sep	32.2 C (90.0 F)	-2.0 C (28.4 F)	n/a	n/a
Oct	28.3 C (82.9 F)	-8.9 C (16.0 F)	n/a	n/a
Nov	22.2 C (72.0 F)	-18.0 C (-0.4 F)	n/a	n/a
Dec	14.0 C (57.2 F)	-38.0 C (-36.4 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Chalk River Aecl still stand. 1964 holds the most, with 97.

Standing records at Chalk River Aecl by the year they were set
Year set	Standing records
1960	17
1961	40
1962	6
1963	80
1964	97
1965	83
1966	78
1967	68
1968	59
1969	12
1970	53
1971	65
1972	66
1973	73
1974	53
1975	54
1976	89
1977	59
1978	57
1979	84
1980	62
1981	73
1982	76
1983	60

Wettest Day of Each Month

Aug: 71.1 mm (2.8 in)

The wettest day on record for each calendar month at Chalk River Aecl. The most was 71.1 mm (2.8 in) on 2 August 1965.

Record daily precipitation for each month at Chalk River Aecl
Month	Record daily precipitation (mm)	Date
Jan	28.5 mm (1.1 in)	13 January 1979
Feb	31.2 mm (1.2 in)	25 February 1965
Mar	49.0 mm (1.9 in)	17 March 1973
Apr	25.7 mm (1.0 in)	14 April 1974
May	52.6 mm (2.1 in)	30 May 1982
Jun	47.0 mm (1.9 in)	11 June 1973
Jul	65.3 mm (2.6 in)	20 July 1970
Aug	71.1 mm (2.8 in)	2 August 1965
Sep	44.7 mm (1.8 in)	28 September 1967
Oct	43.8 mm (1.7 in)	5 October 1979
Nov	41.1 mm (1.6 in)	20 November 1974
Dec	27.2 mm (1.1 in)	12 December 1972

Period of Record Coverage

1960 to 1983

24 years of record at Chalk River Aecl, 1960 to 1983. 4 years have data for under 90 percent of days and are left out of rankings: 1960, 1961, 1962, 1969.

Days with data per year at Chalk River Aecl
Year	Days with data	Share of year	Complete
1960	61	17%	No
1961	239	65%	No
1962	59	16%	No
1963	334	92%	Yes
1964	362	99%	Yes
1965	357	98%	Yes
1966	365	100%	Yes
1967	365	100%	Yes
1968	336	92%	Yes
1969	90	25%	No
1970	332	91%	Yes
1971	359	98%	Yes
1972	356	97%	Yes
1973	355	97%	Yes
1974	365	100%	Yes
1975	365	100%	Yes
1976	366	100%	Yes
1977	365	100%	Yes
1978	365	100%	Yes
1979	365	100%	Yes
1980	364	99%	Yes
1981	363	99%	Yes
1982	364	100%	Yes
1983	364	100%	Yes

Latest Records

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

Climate Trend

17 complete years, 1964 to 1983

One stripe for each of 17 complete years at Chalk River Aecl, 1964 to 1983. Blue stripes are years cooler than the station's own mean of 4.8 C (40.6 F); red stripes are warmer. The coolest year was 1972, at 3.8 C (38.8 F), and the warmest was 1973, at 5.9 C (42.6 F). The strongest colour marks a difference of 1.1 C (2.0 F).

Annual mean temperature at Chalk River Aecl as warming stripes, 1964 to 1983
Year	Annual mean temperature	Difference from the station mean
1964	5.5 C	+0.69 C
1965	4.3 C	-0.48 C
1966	4.9 C	+0.11 C
1967	4.0 C	-0.78 C
1971	5.0 C	+0.22 C
1972	3.8 C	-1.01 C
1973	5.9 C	+1.09 C
1974	4.6 C	-0.17 C
1975	5.6 C	+0.81 C
1976	4.1 C	-0.67 C
1977	5.6 C	+0.80 C
1978	4.3 C	-0.53 C
1979	4.9 C	+0.06 C
1980	3.9 C	-0.93 C
1981	5.5 C	+0.65 C
1982	4.7 C	-0.12 C
1983	5.1 C	+0.28 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

1960 to 1983

Yearly extremes at Chalk River Aecl: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	39.4 C (102.9 F)	1977	33.3 C (91.9 F)	24
Coldest night (TNn)	-39.0 C (-38.2 F)	1981	-34.2 C (-29.6 F)	24
Wettest day (Rx1day)	71.1 mm (2.8 in)	1965	38.5 mm (1.5 in)	22
Wettest five days (Rx5day)	96.1 mm (3.8 in)	1970	62.1 mm (2.4 in)	22
Longest dry spell (CDD)	27 days	1980	16 days	22

Hottest day (TXx)

The hottest day of the year at Chalk River Aecl, 1960 to 1983. The record is 39.4 C (102.9 F) in 1977, marked on the chart; the median year is 33.3 C (91.9 F).

Hottest day (TXx) at Chalk River Aecl by year
Year	Hottest day (TXx)
1960	15.6 C (60.1 F)
1961	32.2 C (90.0 F)
1962	18.3 C (64.9 F)
1963	37.2 C (99.0 F)
1964	35.0 C (95.0 F)
1965	32.2 C (90.0 F)
1966	35.0 C (95.0 F)
1967	31.1 C (88.0 F)
1968	33.3 C (91.9 F)
1969	10.6 C (51.1 F)
1970	31.7 C (89.1 F)
1971	34.4 C (93.9 F)
1972	33.3 C (91.9 F)
1973	33.9 C (93.0 F)
1974	32.8 C (91.0 F)
1975	37.2 C (99.0 F)
1976	33.3 C (91.9 F)
1977	39.4 C (102.9 F)
1978	34.0 C (93.2 F)
1979	32.0 C (89.6 F)
1980	32.0 C (89.6 F)
1981	34.5 C (94.1 F)
1982	33.5 C (92.3 F)
1983	33.5 C (92.3 F)

Coldest night (TNn)

The coldest night of the year at Chalk River Aecl, 1960 to 1983. The record is -39.0 C (-38.2 F) in 1981, marked on the chart; the median year is -34.2 C (-29.6 F).

Coldest night (TNn) at Chalk River Aecl by year
Year	Coldest night (TNn)
1960	-27.8 C (-18.0 F)
1961	-33.3 C (-27.9 F)
1962	-35.6 C (-32.1 F)
1963	-33.3 C (-27.9 F)
1964	-30.0 C (-22.0 F)
1965	-35.0 C (-31.0 F)
1966	-33.9 C (-29.0 F)
1967	-35.0 C (-31.0 F)
1968	-35.0 C (-31.0 F)
1969	-26.7 C (-16.1 F)
1970	-35.6 C (-32.1 F)
1971	-35.0 C (-31.0 F)
1972	-35.6 C (-32.1 F)
1973	-33.9 C (-29.0 F)
1974	-30.6 C (-23.1 F)
1975	-31.7 C (-25.1 F)
1976	-37.2 C (-35.0 F)
1977	-33.3 C (-27.9 F)
1978	-29.0 C (-20.2 F)
1979	-34.5 C (-30.1 F)
1980	-38.0 C (-36.4 F)
1981	-39.0 C (-38.2 F)
1982	-35.0 C (-31.0 F)
1983	-33.0 C (-27.4 F)

Wettest day (Rx1day)

The wettest day of the year at Chalk River Aecl, 1960 to 1983. The record is 71.1 mm (2.8 in) in 1965, marked on the chart; the median year is 38.5 mm (1.5 in).

Wettest day (Rx1day) at Chalk River Aecl by year
Year	Wettest day (Rx1day)
1960	n/a
1961	14.5 mm (0.6 in)
1962	n/a
1963	29.5 mm (1.2 in)
1964	20.3 mm (0.8 in)
1965	71.1 mm (2.8 in)
1966	38.9 mm (1.5 in)
1967	44.7 mm (1.8 in)
1968	37.8 mm (1.5 in)
1969	12.2 mm (0.5 in)
1970	65.3 mm (2.6 in)
1971	28.7 mm (1.1 in)
1972	37.8 mm (1.5 in)
1973	49.0 mm (1.9 in)
1974	41.1 mm (1.6 in)
1975	35.8 mm (1.4 in)
1976	48.8 mm (1.9 in)
1977	29.7 mm (1.2 in)
1978	32.8 mm (1.3 in)
1979	43.8 mm (1.7 in)
1980	40.0 mm (1.6 in)
1981	39.9 mm (1.6 in)
1982	52.6 mm (2.1 in)
1983	38.0 mm (1.5 in)

Wettest five days (Rx5day)

The wettest five days of the year at Chalk River Aecl, 1960 to 1983. The record is 96.1 mm (3.8 in) in 1970, marked on the chart; the median year is 62.1 mm (2.4 in).

Wettest five days (Rx5day) at Chalk River Aecl by year
Year	Wettest five days (Rx5day)
1960	n/a
1961	21.4 mm (0.8 in)
1962	n/a
1963	39.4 mm (1.6 in)
1964	36.8 mm (1.4 in)
1965	91.2 mm (3.6 in)
1966	54.8 mm (2.2 in)
1967	90.9 mm (3.6 in)
1968	74.0 mm (2.9 in)
1969	23.9 mm (0.9 in)
1970	96.1 mm (3.8 in)
1971	42.2 mm (1.7 in)
1972	76.2 mm (3.0 in)
1973	89.7 mm (3.5 in)
1974	53.0 mm (2.1 in)
1975	63.0 mm (2.5 in)
1976	60.4 mm (2.4 in)
1977	48.5 mm (1.9 in)
1978	48.0 mm (1.9 in)
1979	63.0 mm (2.5 in)
1980	61.1 mm (2.4 in)
1981	94.3 mm (3.7 in)
1982	71.5 mm (2.8 in)
1983	64.0 mm (2.5 in)

Longest dry spell (CDD)

The longest dry spell of the year at Chalk River Aecl, 1960 to 1983. The record is 27 days in 1980, marked on the chart; the median year is 16 days.

Longest dry spell (CDD) at Chalk River Aecl by year
Year	Longest dry spell (CDD)
1960	n/a
1961	26 days
1962	n/a
1963	14 days
1964	15 days
1965	19 days
1966	18 days
1967	19 days
1968	13 days
1969	16 days
1970	17 days
1971	14 days
1972	10 days
1973	11 days
1974	12 days
1975	23 days
1976	19 days
1977	18 days
1978	18 days
1979	13 days
1980	27 days
1981	12 days
1982	14 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.

Download the Data

Data for Chalk River Aecl standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Chalk River Aecl 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 2026-10-16 (16 October 2026). Records are computed by this site and are not official.

Data as of 2026-10-16. Last revised 16 October 2026 (2026-10-16).