South Mountain Weather Records (CA006107955)

Record envelope, standing records and threshold days for South Mountain (CA006107955), Ontario, Canada, with 37 years of record.

Key Facts for South Mountain

South Mountain (CA006107955) is a weather station in Ontario, Canada at 44.97 latitude and -75.48 longitude, 85 m (279 ft) above sea level.
The station reports from 1960 to 1996, 37 years of record.
1,464 records set at South Mountain 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, 44.97 latitude, -75.48 longitude.
Elevation: 85 m (279 ft).
Period of record: 1960 to 1996, 37 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 South Mountain. 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 South Mountain, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	12.2 C (54.0 F)	-37.0 C (-34.6 F)	n/a	n/a
Feb	14.5 C (58.1 F)	-36.7 C (-34.1 F)	n/a	n/a
Mar	25.6 C (78.1 F)	-27.0 C (-16.6 F)	n/a	n/a
Apr	29.4 C (84.9 F)	-14.5 C (5.9 F)	n/a	n/a
May	33.3 C (91.9 F)	-6.1 C (21.0 F)	n/a	n/a
Jun	35.0 C (95.0 F)	0.0 C (32.0 F)	n/a	n/a
Jul	34.4 C (93.9 F)	3.9 C (39.0 F)	n/a	n/a
Aug	37.2 C (99.0 F)	0.6 C (33.1 F)	n/a	n/a
Sep	32.5 C (90.5 F)	-4.0 C (24.8 F)	n/a	n/a
Oct	27.8 C (82.0 F)	-8.3 C (17.1 F)	n/a	n/a
Nov	22.8 C (73.0 F)	-20.6 C (-5.1 F)	n/a	n/a
Dec	16.0 C (60.8 F)	-34.0 C (-29.2 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at South Mountain still stand. 1979 holds the most, with 87.

Standing records at South Mountain by the year they were set
Year set	Standing records
1961	28
1962	69
1963	66
1964	83
1965	75
1966	56
1967	78
1968	70
1969	45
1970	62
1971	64
1972	50
1973	66
1974	53
1975	64
1976	79
1977	55
1978	56
1979	87
1980	44
1981	74
1982	70
1983	70

Wettest Day of Each Month

Sep: 68.4 mm (2.7 in)

The wettest day on record for each calendar month at South Mountain. The most was 68.4 mm (2.7 in) on 14 September 1979.

Record daily precipitation for each month at South Mountain
Month	Record daily precipitation (mm)	Date
Jan	51.6 mm (2.0 in)	8 January 1978
Feb	40.6 mm (1.6 in)	13 February 1971
Mar	35.6 mm (1.4 in)	4 March 1971
Apr	38.9 mm (1.5 in)	27 April 1973
May	48.3 mm (1.9 in)	31 May 1960
Jun	56.2 mm (2.2 in)	22 June 1981
Jul	52.3 mm (2.1 in)	29 July 1977
Aug	55.4 mm (2.2 in)	25 August 1982
Sep	68.4 mm (2.7 in)	14 September 1979
Oct	60.8 mm (2.4 in)	25 October 1980
Nov	41.1 mm (1.6 in)	29 November 1963
Dec	50.8 mm (2.0 in)	9 December 1973

Period of Record Coverage

1961 to 1983

23 years of record at South Mountain, 1961 to 1983. 1 years have data for under 90 percent of days and are left out of rankings: 1961.

Days with data per year at South Mountain
Year	Days with data	Share of year	Complete
1961	184	50%	No
1962	365	100%	Yes
1963	365	100%	Yes
1964	366	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	365	100%	Yes
1972	366	100%	Yes
1973	365	100%	Yes
1974	365	100%	Yes
1975	365	100%	Yes
1976	366	100%	Yes
1977	337	92%	Yes
1978	365	100%	Yes
1979	365	100%	Yes
1980	366	100%	Yes
1981	365	100%	Yes
1982	365	100%	Yes
1983	364	100%	Yes

Latest Records

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

Climate Trend

21 complete years, 1962 to 1983

One stripe for each of 21 complete years at South Mountain, 1962 to 1983. Blue stripes are years cooler than the station's own mean of 5.8 C (42.5 F); red stripes are warmer. The coolest year was 1972, at 5.0 C (40.9 F), and the warmest was 1973, at 7.1 C (44.8 F). The strongest colour marks a difference of 1.4 C (2.5 F).

Annual mean temperature at South Mountain as warming stripes, 1962 to 1983
Year	Annual mean temperature	Difference from the station mean
1962	5.3 C	-0.56 C
1963	5.3 C	-0.57 C
1964	6.4 C	+0.60 C
1965	5.6 C	-0.27 C
1966	5.9 C	+0.10 C
1967	5.6 C	-0.25 C
1968	5.6 C	-0.27 C
1969	6.0 C	+0.16 C
1970	5.4 C	-0.41 C
1971	5.6 C	-0.22 C
1972	5.0 C	-0.85 C
1973	7.1 C	+1.31 C
1974	5.7 C	-0.12 C
1975	6.7 C	+0.87 C
1976	5.2 C	-0.58 C
1978	5.2 C	-0.65 C
1979	6.4 C	+0.58 C
1980	5.4 C	-0.44 C
1981	6.7 C	+0.85 C
1982	5.8 C	-0.04 C
1983	6.7 C	+0.85 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 South Mountain: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	37.2 C (99.0 F)	1975	32.8 C (91.0 F)	23
Coldest night (TNn)	-37.0 C (-34.6 F)	1981	-32.2 C (-26.0 F)	23
Wettest day (Rx1day)	68.4 mm (2.7 in)	1979	46.7 mm (1.8 in)	24
Wettest five days (Rx5day)	106.7 mm (4.2 in)	1979	65.8 mm (2.6 in)	24
Longest dry spell (CDD)	21 days	1961	15 days	24

Hottest day (TXx)

The hottest day of the year at South Mountain, 1960 to 1983. The record is 37.2 C (99.0 F) in 1975, marked on the chart; the median year is 32.8 C (91.0 F).

Hottest day (TXx) at South Mountain by year
Year	Hottest day (TXx)
1960	n/a
1961	31.7 C (89.1 F)
1962	32.8 C (91.0 F)
1963	34.4 C (93.9 F)
1964	35.0 C (95.0 F)
1965	32.8 C (91.0 F)
1966	33.9 C (93.0 F)
1967	31.1 C (88.0 F)
1968	33.3 C (91.9 F)
1969	31.7 C (89.1 F)
1970	31.7 C (89.1 F)
1971	32.2 C (90.0 F)
1972	31.1 C (88.0 F)
1973	32.8 C (91.0 F)
1974	31.7 C (89.1 F)
1975	37.2 C (99.0 F)
1976	32.2 C (90.0 F)
1977	33.3 C (91.9 F)
1978	33.0 C (91.4 F)
1979	32.5 C (90.5 F)
1980	31.5 C (88.7 F)
1981	33.0 C (91.4 F)
1982	32.0 C (89.6 F)
1983	33.0 C (91.4 F)

Coldest night (TNn)

The coldest night of the year at South Mountain, 1960 to 1983. The record is -37.0 C (-34.6 F) in 1981, marked on the chart; the median year is -32.2 C (-26.0 F).

Coldest night (TNn) at South Mountain by year
Year	Coldest night (TNn)
1960	n/a
1961	-19.4 C (-2.9 F)
1962	-32.2 C (-26.0 F)
1963	-34.4 C (-29.9 F)
1964	-31.7 C (-25.1 F)
1965	-30.6 C (-23.1 F)
1966	-30.6 C (-23.1 F)
1967	-33.3 C (-27.9 F)
1968	-33.3 C (-27.9 F)
1969	-26.7 C (-16.1 F)
1970	-32.2 C (-26.0 F)
1971	-36.7 C (-34.1 F)
1972	-35.6 C (-32.1 F)
1973	-31.7 C (-25.1 F)
1974	-30.6 C (-23.1 F)
1975	-28.9 C (-20.0 F)
1976	-33.9 C (-29.0 F)
1977	-32.2 C (-26.0 F)
1978	-30.6 C (-23.1 F)
1979	-34.0 C (-29.2 F)
1980	-34.0 C (-29.2 F)
1981	-37.0 C (-34.6 F)
1982	-32.0 C (-25.6 F)
1983	-27.0 C (-16.6 F)

Wettest day (Rx1day)

The wettest day of the year at South Mountain, 1960 to 1983. The record is 68.4 mm (2.7 in) in 1979, marked on the chart; the median year is 46.7 mm (1.8 in).

Wettest day (Rx1day) at South Mountain by year
Year	Wettest day (Rx1day)
1960	48.3 mm (1.9 in)
1961	39.4 mm (1.6 in)
1962	30.5 mm (1.2 in)
1963	54.6 mm (2.1 in)
1964	33.0 mm (1.3 in)
1965	30.2 mm (1.2 in)
1966	43.2 mm (1.7 in)
1967	37.3 mm (1.5 in)
1968	39.4 mm (1.6 in)
1969	61.7 mm (2.4 in)
1970	37.6 mm (1.5 in)
1971	40.6 mm (1.6 in)
1972	51.8 mm (2.0 in)
1973	50.8 mm (2.0 in)
1974	33.5 mm (1.3 in)
1975	65.5 mm (2.6 in)
1976	42.7 mm (1.7 in)
1977	52.3 mm (2.1 in)
1978	51.6 mm (2.0 in)
1979	68.4 mm (2.7 in)
1980	60.8 mm (2.4 in)
1981	56.2 mm (2.2 in)
1982	55.4 mm (2.2 in)
1983	45.0 mm (1.8 in)

Wettest five days (Rx5day)

The wettest five days of the year at South Mountain, 1960 to 1983. The record is 106.7 mm (4.2 in) in 1979, marked on the chart; the median year is 65.8 mm (2.6 in).

Wettest five days (Rx5day) at South Mountain by year
Year	Wettest five days (Rx5day)
1960	62.8 mm (2.5 in)
1961	65.3 mm (2.6 in)
1962	59.0 mm (2.3 in)
1963	73.2 mm (2.9 in)
1964	39.1 mm (1.5 in)
1965	54.4 mm (2.1 in)
1966	55.3 mm (2.2 in)
1967	60.9 mm (2.4 in)
1968	59.0 mm (2.3 in)
1969	76.7 mm (3.0 in)
1970	66.3 mm (2.6 in)
1971	67.1 mm (2.6 in)
1972	82.6 mm (3.3 in)
1973	78.5 mm (3.1 in)
1974	49.1 mm (1.9 in)
1975	79.0 mm (3.1 in)
1976	53.6 mm (2.1 in)
1977	63.8 mm (2.5 in)
1978	70.1 mm (2.8 in)
1979	106.7 mm (4.2 in)
1980	63.6 mm (2.5 in)
1981	80.4 mm (3.2 in)
1982	68.6 mm (2.7 in)
1983	78.8 mm (3.1 in)

Longest dry spell (CDD)

The longest dry spell of the year at South Mountain, 1960 to 1983. The record is 21 days in 1961, marked on the chart; the median year is 15 days.

Longest dry spell (CDD) at South Mountain by year
Year	Longest dry spell (CDD)
1960	14 days
1961	21 days
1962	13 days
1963	19 days
1964	21 days
1965	18 days
1966	12 days
1967	17 days
1968	12 days
1969	12 days
1970	18 days
1971	11 days
1972	13 days
1973	14 days
1974	17 days
1975	17 days
1976	12 days
1977	18 days
1978	17 days
1979	12 days
1980	14 days
1981	8 days
1982	17 days
1983	16 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

21 years with a frost

Across 21 years with a frost, the median last spring frost at South Mountain falls on 8 May and the median first autumn frost on 24 September, which leaves a median of 136 days between them.

Frost dates and growing season at South Mountain
Measure	Median, all years	Earliest period	Recent period (1962 to 1983)	Recent against earliest	Fitted trend
Last spring frost	8 May	n/a	8 May	n/a	n/a
First autumn frost	24 September	n/a	24 September	n/a	n/a
Growing days	136 days	n/a	136 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 South Mountain standing records by year: CSV or JSON. Field meanings are on the data page.
Data for South Mountain 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).