Guelph Oac Weather Records (CA006143083)

Record envelope, standing records and threshold days for Guelph Oac (CA006143083), Ontario, Canada, with 93 years of record.

Key Facts for Guelph Oac

Guelph Oac (CA006143083) is a weather station in Ontario, Canada at 43.52 latitude and -80.23 longitude, 334 m (1,096 ft) above sea level.
The station reports from 1881 to 1973, 93 years of record.
1,464 records set at Guelph Oac still stand.
Records are tracked for tmax, tmin, prcp, snow: an element needs 30 years of data to be eligible.
Guelph Oac set a daily record precipitation of 21.1 mm (0.8 in) on 14 November 1973.

About the Station

Location: Ontario, Canada, 43.52 latitude, -80.23 longitude.
Elevation: 334 m (1,096 ft).
Period of record: 1881 to 1973, 93 years.
Eligible elements: tmax, tmin, prcp, snow.

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 Guelph Oac. 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 Guelph Oac, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	16.7 C (62.1 F)	-37.2 C (-35.0 F)	n/a	n/a
Feb	13.9 C (57.0 F)	-32.8 C (-27.0 F)	n/a	n/a
Mar	24.4 C (75.9 F)	-28.9 C (-20.0 F)	n/a	n/a
Apr	28.9 C (84.0 F)	-16.1 C (3.0 F)	n/a	n/a
May	32.2 C (90.0 F)	-7.8 C (18.0 F)	n/a	n/a
Jun	35.0 C (95.0 F)	-1.1 C (30.0 F)	n/a	n/a
Jul	38.3 C (100.9 F)	1.7 C (35.1 F)	n/a	n/a
Aug	38.3 C (100.9 F)	-1.1 C (30.0 F)	n/a	n/a
Sep	36.7 C (98.1 F)	-6.7 C (19.9 F)	n/a	n/a
Oct	29.4 C (84.9 F)	-12.8 C (9.0 F)	n/a	n/a
Nov	23.9 C (75.0 F)	-20.6 C (-5.1 F)	n/a	n/a
Dec	16.1 C (61.0 F)	-31.1 C (-24.0 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Guelph Oac still stand. 1885 holds the most, with 33.

Standing records at Guelph Oac by the year they were set
Year set	Standing records
1881	23
1882	16
1883	19
1884	29
1885	33
1886	23
1887	20
1888	23
1889	27
1890	10
1891	28
1892	33
1893	26
1899	22
1900	29
1901	8
1902	12
1903	28
1904	20
1905	11
1906	13
1907	6
1908	16
1909	15
1910	21
1911	26
1912	9
1913	11
1914	20
1915	13
1916	18
1917	21
1918	16
1919	12
1920	20
1921	15
1922	9
1923	18
1924	9
1925	17
1926	20
1927	21
1928	10
1929	16
1930	22
1931	17
1932	16
1933	28
1934	22
1935	6
1936	27
1937	11
1938	19
1939	11
1940	16
1941	16
1942	13
1943	13
1944	10
1945	23
1946	22
1947	17
1948	15
1949	23
1950	18
1951	16
1952	10
1953	13
1954	12
1955	17
1956	15
1957	10
1958	9
1959	12
1960	9
1961	8
1962	11
1963	18
1964	20
1965	19
1966	14
1967	11
1968	8
1969	10
1970	5
1971	9
1972	18
1973	13

All-Time Record Progression

5 new records

5 all-time records were set at Guelph Oac between 6 August 1918 and 24 November 1950. Each dot is a new record.

When Guelph Oac set new all-time records
Date	Kind	Detail
1918-08-06	Record high maximum temperature	Record high maximum temperature 38.3 C (100.9 F)
1921-07-10	Record daily precipitation	Record daily precipitation 83.6 mm (3.3 in)
1934-02-08	Record low maximum temperature	Record low maximum temperature -25.6 C (-14.1 F)
1938-08-10	Record daily precipitation	Record daily precipitation 103.4 mm (4.1 in)
1950-11-24	Record daily snowfall	Record daily snowfall 55.1 cm (21.7 in)

Wettest Day of Each Month

Aug: 103.4 mm (4.1 in)

The wettest day on record for each calendar month at Guelph Oac. The most was 103.4 mm (4.1 in) on 10 August 1938.

Record daily precipitation for each month at Guelph Oac
Month	Record daily precipitation (mm)	Date
Jan	54.4 mm (2.1 in)	4 January 1922
Feb	63.5 mm (2.5 in)	5 February 1938
Mar	43.2 mm (1.7 in)	31 March 1926
Apr	45.2 mm (1.8 in)	2 April 1967
May	66.0 mm (2.6 in)	25 May 1953
Jun	74.7 mm (2.9 in)	11 June 1922
Jul	83.6 mm (3.3 in)	10 July 1921
Aug	103.4 mm (4.1 in)	10 August 1938
Sep	52.8 mm (2.1 in)	11 September 1922
Oct	95.8 mm (3.8 in)	15 October 1954
Nov	57.2 mm (2.3 in)	2 November 1940
Dec	50.3 mm (2.0 in)	12 December 1972

Period of Record Coverage

1881 to 1973

88 years of record at Guelph Oac, 1881 to 1973. 2 years have data for under 90 percent of days and are left out of rankings: 1881, 1890.

Days with data per year at Guelph Oac
Year	Days with data	Share of year	Complete
1881	234	64%	No
1882	359	98%	Yes
1883	363	99%	Yes
1884	364	99%	Yes
1885	329	90%	Yes
1886	364	100%	Yes
1887	362	99%	Yes
1888	363	99%	Yes
1889	358	98%	Yes
1890	320	88%	No
1891	363	99%	Yes
1892	359	98%	Yes
1893	355	97%	Yes
1899	363	99%	Yes
1900	361	99%	Yes
1901	352	96%	Yes
1902	351	96%	Yes
1903	351	96%	Yes
1904	365	100%	Yes
1905	359	98%	Yes
1906	358	98%	Yes
1907	358	98%	Yes
1908	357	98%	Yes
1909	362	99%	Yes
1910	365	100%	Yes
1911	360	99%	Yes
1912	362	99%	Yes
1913	365	100%	Yes
1914	364	100%	Yes
1915	362	99%	Yes
1916	356	97%	Yes
1917	365	100%	Yes
1918	361	99%	Yes
1919	362	99%	Yes
1920	364	99%	Yes
1921	359	98%	Yes
1922	360	99%	Yes
1923	361	99%	Yes
1924	365	100%	Yes
1925	363	99%	Yes
1926	363	99%	Yes
1927	364	100%	Yes
1928	364	99%	Yes
1929	364	100%	Yes
1930	360	99%	Yes
1931	362	99%	Yes
1932	366	100%	Yes
1933	361	99%	Yes
1934	359	98%	Yes
1935	363	99%	Yes
1936	366	100%	Yes
1937	365	100%	Yes
1938	365	100%	Yes
1939	365	100%	Yes
1940	364	99%	Yes
1941	356	98%	Yes
1942	365	100%	Yes
1943	365	100%	Yes
1944	363	99%	Yes
1945	361	99%	Yes
1946	365	100%	Yes
1947	365	100%	Yes
1948	366	100%	Yes
1949	365	100%	Yes
1950	361	99%	Yes
1951	364	100%	Yes
1952	362	99%	Yes
1953	364	100%	Yes
1954	365	100%	Yes
1955	365	100%	Yes
1956	366	100%	Yes
1957	365	100%	Yes
1958	365	100%	Yes
1959	364	100%	Yes
1960	365	100%	Yes
1961	365	100%	Yes
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	334	92%	Yes

Latest Records

Latest records at Guelph Oac
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
14 November 1973	Guelph Oac, CA	daily rain	21.1 mm (0.8 in)	3.8 mm (0.15 in)	80 years	20 of 100 (Routine)
29 October 1973	Guelph Oac, CA	daily rain	24.1 mm (0.9 in)	8.1 mm (0.32 in)	18 years	20 of 100 (Routine)
21 September 1973	Guelph Oac, CA	daily low min	-2.8 C (27.0 F)	2.8 C (5.0 F)	16 years	19 of 100 (Routine)
17 September 1973	Guelph Oac, CA	daily low min	-0.6 C (30.9 F)	0.6 C (1.1 F)	50 years	25 of 100 (Routine)
29 August 1973	Guelph Oac, CA	daily high max (Tie)	32.2 C (90.0 F)	tie	91 years	9 of 100 (Routine)
28 August 1973	Guelph Oac, CA	daily high min	22.2 C (72.0 F)	1.6 C (2.9 F)	14 years	16 of 100 (Routine)
27 August 1973	Guelph Oac, CA	daily high min	21.1 C (70.0 F)	1.1 C (2.0 F)	72 years	32 of 100 (Routine)
9 August 1973	Guelph Oac, CA	daily high min	22.8 C (73.0 F)	2.2 C (4.0 F)	55 years	30 of 100 (Routine)
25 July 1973	Guelph Oac, CA	daily rain	21.8 mm (0.9 in)	4.5 mm (0.18 in)	11 years	15 of 100 (Routine)
17 June 1973	Guelph Oac, CA	daily low max	14.4 C (57.9 F)	2.8 C (5.0 F)	14 years	19 of 100 (Routine)
27 April 1973	Guelph Oac, CA	daily rain	17.5 mm (0.7 in)	1.2 mm (0.05 in)	16 years	15 of 100 (Routine)
22 April 1973	Guelph Oac, CA	monthly high min	16.7 C (62.1 F)	1.1 C (2.0 F)	57 years	38 of 100 (Notable)
21 April 1973	Guelph Oac, CA	daily high max	25.0 C (77.0 F)	0.6 C (1.1 F)	86 years	35 of 100 (Notable)
17 March 1973	Guelph Oac, CA	daily rain	29.7 mm (1.2 in)	12.9 mm (0.5 in)	8 years	32 of 100 (Routine)
17 March 1973	Guelph Oac, CA	daily snowfall	23.4 cm (9.2 in)	6.6 cm (2.6 in)	8 years	26 of 100 (Routine)
15 March 1973	Guelph Oac, CA	daily high max (Tie)	17.8 C (64.0 F)	tie	28 years	4 of 100 (Routine)
12 March 1973	Guelph Oac, CA	daily high min	3.9 C (39.0 F)	1.1 C (2.0 F)	46 years	23 of 100 (Routine)
11 March 1973	Guelph Oac, CA	daily rain	30.2 mm (1.2 in)	16.2 mm (0.6 in)	36 years	47 of 100 (Notable)
7 March 1973	Guelph Oac, CA	daily high min	4.4 C (39.9 F)	3.3 C (5.9 F)	27 years	22 of 100 (Routine)
7 March 1973	Guelph Oac, CA	daily high max (Tie)	10.6 C (51.1 F)	tie	63 years	6 of 100 (Routine)

Climate Trend

83 complete years, 1882 to 1972

One stripe for each of 83 complete years at Guelph Oac, 1882 to 1972. Blue stripes are years cooler than the station's own mean of 6.7 C (44.0 F); red stripes are warmer. The coolest year was 1904, at 4.8 C (40.6 F), and the warmest was 1921, at 8.5 C (47.3 F). The strongest colour marks a difference of 1.9 C (3.4 F).

Annual mean temperature at Guelph Oac as warming stripes, 1882 to 1972
Year	Annual mean temperature	Difference from the station mean
1882	7.4 C	+0.68 C
1883	5.5 C	-1.16 C
1884	6.3 C	-0.40 C
1886	6.1 C	-0.58 C
1887	6.4 C	-0.33 C
1888	5.5 C	-1.17 C
1889	6.7 C	+0.04 C
1891	7.6 C	+0.91 C
1893	5.0 C	-1.66 C
1899	7.1 C	+0.46 C
1900	7.8 C	+1.10 C
1901	6.5 C	-0.23 C
1902	6.4 C	-0.24 C
1903	6.8 C	+0.10 C
1904	4.8 C	-1.90 C
1905	6.5 C	-0.21 C
1906	7.4 C	+0.73 C
1907	6.4 C	-0.28 C
1908	7.4 C	+0.69 C
1909	6.8 C	+0.14 C
1910	6.9 C	+0.23 C
1911	7.6 C	+0.91 C
1912	6.0 C	-0.65 C
1913	7.9 C	+1.17 C
1914	6.8 C	+0.14 C
1915	7.0 C	+0.36 C
1916	6.9 C	+0.22 C
1917	4.8 C	-1.89 C
1918	6.8 C	+0.11 C
1919	7.6 C	+0.89 C
1920	6.0 C	-0.67 C
1921	8.5 C	+1.83 C
1922	7.4 C	+0.72 C
1923	6.3 C	-0.42 C
1924	5.4 C	-1.31 C
1925	6.2 C	-0.52 C
1926	4.9 C	-1.78 C
1927	6.8 C	+0.12 C
1928	6.5 C	-0.20 C
1929	6.0 C	-0.73 C
1930	6.8 C	+0.13 C
1931	8.1 C	+1.39 C
1932	7.1 C	+0.42 C
1933	7.3 C	+0.65 C
1934	6.3 C	-0.39 C
1935	6.3 C	-0.39 C
1936	6.4 C	-0.25 C
1937	7.0 C	+0.29 C
1938	7.7 C	+1.06 C
1939	6.9 C	+0.25 C
1940	5.7 C	-0.96 C
1941	7.6 C	+0.89 C
1942	6.9 C	+0.22 C
1943	5.9 C	-0.77 C
1944	6.6 C	-0.06 C
1945	6.3 C	-0.35 C
1946	7.5 C	+0.84 C
1947	7.1 C	+0.42 C
1948	7.3 C	+0.60 C
1949	8.3 C	+1.62 C
1950	6.5 C	-0.22 C
1951	7.1 C	+0.40 C
1952	7.7 C	+1.00 C
1953	8.1 C	+1.37 C
1954	7.0 C	+0.30 C
1955	7.7 C	+0.99 C
1956	6.5 C	-0.20 C
1957	6.9 C	+0.19 C
1958	6.3 C	-0.34 C
1959	7.2 C	+0.49 C
1960	6.5 C	-0.14 C
1961	6.9 C	+0.21 C
1962	6.2 C	-0.52 C
1963	5.9 C	-0.83 C
1964	6.6 C	-0.11 C
1965	5.8 C	-0.84 C
1966	6.4 C	-0.33 C
1967	6.0 C	-0.67 C
1968	6.5 C	-0.19 C
1969	6.7 C	+0.00 C
1970	6.3 C	-0.38 C
1971	6.7 C	-0.03 C
1972	5.6 C	-1.10 C

The fitted trend in annual mean temperature here over 1882 to 1972 is 0.02 C (-0.05 to 0.09) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.03 F (-0.09 to 0.15) per decade. The slope is a straight line fitted to 83 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Guelph Oac
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	0.02 C (-0.05 to 0.09) per decade	0.03 F (-0.09 to 0.15) per decade	1882 to 1972	83	Not clearly different from zero
Mean daily maximum	-0.05 C (-0.12 to 0.03) per decade	-0.08 F (-0.22 to 0.05) per decade	1882 to 1972	83	Not clearly different from zero
Mean daily minimum	0.08 C (0.01 to 0.16) per decade	0.15 F (0.01 to 0.29) per decade	1882 to 1972	83	Rise

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

1881 to 1973

Yearly extremes at Guelph Oac: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	38.3 C (100.9 F)	1918	32.8 C (91.0 F)	88
Coldest night (TNn)	-37.2 C (-35.0 F)	1884	-25.6 C (-14.1 F)	88
Wettest day (Rx1day)	103.4 mm (4.1 in)	1938	43.2 mm (1.7 in)	88
Wettest five days (Rx5day)	164.2 mm (6.5 in)	1954	65.3 mm (2.6 in)	88
Longest dry spell (CDD)	38 days	1885	18 days	88

Hottest day (TXx)

The hottest day of the year at Guelph Oac, 1881 to 1973. The record is 38.3 C (100.9 F) in 1918, marked on the chart; the median year is 32.8 C (91.0 F).

Hottest day (TXx) at Guelph Oac by year
Year	Hottest day (TXx)
1881	36.7 C (98.1 F)
1882	32.2 C (90.0 F)
1883	31.7 C (89.1 F)
1884	33.9 C (93.0 F)
1885	32.2 C (90.0 F)
1886	33.3 C (91.9 F)
1887	35.6 C (96.1 F)
1888	35.0 C (95.0 F)
1889	31.7 C (89.1 F)
1890	36.7 C (98.1 F)
1891	35.0 C (95.0 F)
1892	33.3 C (91.9 F)
1893	34.4 C (93.9 F)
1899	35.0 C (95.0 F)
1900	35.6 C (96.1 F)
1901	34.4 C (93.9 F)
1902	31.7 C (89.1 F)
1903	32.2 C (90.0 F)
1904	32.2 C (90.0 F)
1905	31.7 C (89.1 F)
1906	31.7 C (89.1 F)
1907	31.1 C (88.0 F)
1908	31.7 C (89.1 F)
1909	34.4 C (93.9 F)
1910	33.9 C (93.0 F)
1911	37.2 C (99.0 F)
1912	31.7 C (89.1 F)
1913	35.0 C (95.0 F)
1914	33.9 C (93.0 F)
1915	30.0 C (86.0 F)
1916	36.1 C (97.0 F)
1917	34.4 C (93.9 F)
1918	38.3 C (100.9 F)
1919	34.4 C (93.9 F)
1920	31.7 C (89.1 F)
1921	34.4 C (93.9 F)
1922	32.8 C (91.0 F)
1923	32.8 C (91.0 F)
1924	32.8 C (91.0 F)
1925	32.2 C (90.0 F)
1926	33.3 C (91.9 F)
1927	32.2 C (90.0 F)
1928	31.1 C (88.0 F)
1929	32.8 C (91.0 F)
1930	33.3 C (91.9 F)
1931	36.1 C (97.0 F)
1932	32.2 C (90.0 F)
1933	35.6 C (96.1 F)
1934	33.9 C (93.0 F)
1935	32.2 C (90.0 F)
1936	38.3 C (100.9 F)
1937	32.2 C (90.0 F)
1938	32.8 C (91.0 F)
1939	34.4 C (93.9 F)
1940	31.7 C (89.1 F)
1941	34.4 C (93.9 F)
1942	32.2 C (90.0 F)
1943	31.7 C (89.1 F)
1944	34.4 C (93.9 F)
1945	32.2 C (90.0 F)
1946	33.3 C (91.9 F)
1947	34.4 C (93.9 F)
1948	35.6 C (96.1 F)
1949	35.0 C (95.0 F)
1950	32.2 C (90.0 F)
1951	32.2 C (90.0 F)
1952	34.4 C (93.9 F)
1953	35.0 C (95.0 F)
1954	31.1 C (88.0 F)
1955	36.7 C (98.1 F)
1956	32.2 C (90.0 F)
1957	32.2 C (90.0 F)
1958	31.1 C (88.0 F)
1959	32.8 C (91.0 F)
1960	31.1 C (88.0 F)
1961	30.0 C (86.0 F)
1962	31.1 C (88.0 F)
1963	33.3 C (91.9 F)
1964	32.8 C (91.0 F)
1965	32.2 C (90.0 F)
1966	33.9 C (93.0 F)
1967	31.1 C (88.0 F)
1968	31.7 C (89.1 F)
1969	32.2 C (90.0 F)
1970	30.6 C (87.1 F)
1971	33.3 C (91.9 F)
1972	31.1 C (88.0 F)
1973	33.9 C (93.0 F)

Coldest night (TNn)

The coldest night of the year at Guelph Oac, 1881 to 1973. The record is -37.2 C (-35.0 F) in 1884, marked on the chart; the median year is -25.6 C (-14.1 F).

Coldest night (TNn) at Guelph Oac by year
Year	Coldest night (TNn)
1881	-13.3 C (8.1 F)
1882	-24.4 C (-11.9 F)
1883	-26.7 C (-16.1 F)
1884	-37.2 C (-35.0 F)
1885	-28.9 C (-20.0 F)
1886	-31.1 C (-24.0 F)
1887	-25.6 C (-14.1 F)
1888	-28.3 C (-18.9 F)
1889	-28.3 C (-18.9 F)
1890	-20.0 C (-4.0 F)
1891	-18.3 C (-0.9 F)
1892	-28.9 C (-20.0 F)
1893	-32.2 C (-26.0 F)
1899	-29.4 C (-20.9 F)
1900	-26.1 C (-15.0 F)
1901	-25.6 C (-14.1 F)
1902	-21.7 C (-7.1 F)
1903	-23.3 C (-9.9 F)
1904	-31.7 C (-25.1 F)
1905	-26.1 C (-15.0 F)
1906	-26.1 C (-15.0 F)
1907	-26.1 C (-15.0 F)
1908	-28.3 C (-18.9 F)
1909	-24.4 C (-11.9 F)
1910	-25.6 C (-14.1 F)
1911	-18.3 C (-0.9 F)
1912	-29.4 C (-20.9 F)
1913	-20.6 C (-5.1 F)
1914	-30.6 C (-23.1 F)
1915	-20.6 C (-5.1 F)
1916	-30.0 C (-22.0 F)
1917	-26.7 C (-16.1 F)
1918	-31.7 C (-25.1 F)
1919	-22.2 C (-8.0 F)
1920	-28.9 C (-20.0 F)
1921	-23.9 C (-11.0 F)
1922	-21.1 C (-6.0 F)
1923	-24.4 C (-11.9 F)
1924	-23.9 C (-11.0 F)
1925	-30.0 C (-22.0 F)
1926	-26.1 C (-15.0 F)
1927	-26.7 C (-16.1 F)
1928	-28.9 C (-20.0 F)
1929	-30.0 C (-22.0 F)
1930	-25.0 C (-13.0 F)
1931	-22.2 C (-8.0 F)
1932	-17.8 C (0.0 F)
1933	-28.3 C (-18.9 F)
1934	-32.8 C (-27.0 F)
1935	-25.6 C (-14.1 F)
1936	-25.6 C (-14.1 F)
1937	-18.3 C (-0.9 F)
1938	-21.7 C (-7.1 F)
1939	-27.8 C (-18.0 F)
1940	-26.1 C (-15.0 F)
1941	-28.3 C (-18.9 F)
1942	-31.1 C (-24.0 F)
1943	-29.4 C (-20.9 F)
1944	-26.7 C (-16.1 F)
1945	-29.4 C (-20.9 F)
1946	-23.9 C (-11.0 F)
1947	-19.4 C (-2.9 F)
1948	-30.6 C (-23.1 F)
1949	-21.1 C (-6.0 F)
1950	-26.7 C (-16.1 F)
1951	-21.7 C (-7.1 F)
1952	-22.8 C (-9.0 F)
1953	-19.4 C (-2.9 F)
1954	-23.9 C (-11.0 F)
1955	-24.4 C (-11.9 F)
1956	-20.6 C (-5.1 F)
1957	-26.1 C (-15.0 F)
1958	-25.0 C (-13.0 F)
1959	-24.4 C (-11.9 F)
1960	-23.3 C (-9.9 F)
1961	-25.0 C (-13.0 F)
1962	-23.9 C (-11.0 F)
1963	-28.9 C (-20.0 F)
1964	-23.9 C (-11.0 F)
1965	-26.7 C (-16.1 F)
1966	-26.1 C (-15.0 F)
1967	-30.0 C (-22.0 F)
1968	-25.6 C (-14.1 F)
1969	-21.1 C (-6.0 F)
1970	-28.3 C (-18.9 F)
1971	-23.9 C (-11.0 F)
1972	-23.3 C (-9.9 F)
1973	-22.2 C (-8.0 F)

Wettest day (Rx1day)

The wettest day of the year at Guelph Oac, 1881 to 1973. The record is 103.4 mm (4.1 in) in 1938, marked on the chart; the median year is 43.2 mm (1.7 in).

Wettest day (Rx1day) at Guelph Oac by year
Year	Wettest day (Rx1day)
1881	31.5 mm (1.2 in)
1882	48.3 mm (1.9 in)
1883	43.2 mm (1.7 in)
1884	43.2 mm (1.7 in)
1885	30.2 mm (1.2 in)
1886	36.3 mm (1.4 in)
1887	44.2 mm (1.7 in)
1888	32.5 mm (1.3 in)
1889	38.1 mm (1.5 in)
1890	36.8 mm (1.4 in)
1891	57.2 mm (2.3 in)
1892	35.6 mm (1.4 in)
1893	53.3 mm (2.1 in)
1899	29.5 mm (1.2 in)
1900	43.2 mm (1.7 in)
1901	41.4 mm (1.6 in)
1902	49.5 mm (1.9 in)
1903	35.1 mm (1.4 in)
1904	53.8 mm (2.1 in)
1905	42.9 mm (1.7 in)
1906	60.2 mm (2.4 in)
1907	37.3 mm (1.5 in)
1908	28.2 mm (1.1 in)
1909	42.9 mm (1.7 in)
1910	33.3 mm (1.3 in)
1911	30.0 mm (1.2 in)
1912	51.3 mm (2.0 in)
1913	35.3 mm (1.4 in)
1914	40.4 mm (1.6 in)
1915	42.2 mm (1.7 in)
1916	48.8 mm (1.9 in)
1917	45.7 mm (1.8 in)
1918	49.5 mm (1.9 in)
1919	49.5 mm (1.9 in)
1920	43.2 mm (1.7 in)
1921	83.6 mm (3.3 in)
1922	74.7 mm (2.9 in)
1923	45.7 mm (1.8 in)
1924	36.8 mm (1.4 in)
1925	35.6 mm (1.4 in)
1926	50.8 mm (2.0 in)
1927	55.9 mm (2.2 in)
1928	38.1 mm (1.5 in)
1929	35.6 mm (1.4 in)
1930	35.8 mm (1.4 in)
1931	30.5 mm (1.2 in)
1932	43.2 mm (1.7 in)
1933	31.8 mm (1.3 in)
1934	31.8 mm (1.3 in)
1935	44.2 mm (1.7 in)
1936	59.7 mm (2.4 in)
1937	48.0 mm (1.9 in)
1938	103.4 mm (4.1 in)
1939	31.0 mm (1.2 in)
1940	57.2 mm (2.3 in)
1941	48.3 mm (1.9 in)
1942	54.4 mm (2.1 in)
1943	35.6 mm (1.4 in)
1944	50.8 mm (2.0 in)
1945	47.0 mm (1.9 in)
1946	22.9 mm (0.9 in)
1947	50.8 mm (2.0 in)
1948	37.1 mm (1.5 in)
1949	46.5 mm (1.8 in)
1950	55.1 mm (2.2 in)
1951	62.0 mm (2.4 in)
1952	41.1 mm (1.6 in)
1953	66.0 mm (2.6 in)
1954	95.8 mm (3.8 in)
1955	49.0 mm (1.9 in)
1956	57.7 mm (2.3 in)
1957	51.3 mm (2.0 in)
1958	42.4 mm (1.7 in)
1959	28.4 mm (1.1 in)
1960	35.1 mm (1.4 in)
1961	59.9 mm (2.4 in)
1962	31.8 mm (1.3 in)
1963	31.8 mm (1.3 in)
1964	51.3 mm (2.0 in)
1965	40.6 mm (1.6 in)
1966	46.2 mm (1.8 in)
1967	45.2 mm (1.8 in)
1968	79.5 mm (3.1 in)
1969	46.2 mm (1.8 in)
1970	33.5 mm (1.3 in)
1971	61.0 mm (2.4 in)
1972	50.3 mm (2.0 in)
1973	33.3 mm (1.3 in)

Wettest five days (Rx5day)

The wettest five days of the year at Guelph Oac, 1881 to 1973. The record is 164.2 mm (6.5 in) in 1954, marked on the chart; the median year is 65.3 mm (2.6 in).

Wettest five days (Rx5day) at Guelph Oac by year
Year	Wettest five days (Rx5day)
1881	49.3 mm (1.9 in)
1882	50.5 mm (2.0 in)
1883	43.5 mm (1.7 in)
1884	56.8 mm (2.2 in)
1885	33.3 mm (1.3 in)
1886	47.2 mm (1.9 in)
1887	44.2 mm (1.7 in)
1888	50.7 mm (2.0 in)
1889	70.1 mm (2.8 in)
1890	63.8 mm (2.5 in)
1891	61.0 mm (2.4 in)
1892	53.9 mm (2.1 in)
1893	54.4 mm (2.1 in)
1899	37.9 mm (1.5 in)
1900	51.4 mm (2.0 in)
1901	75.4 mm (3.0 in)
1902	65.3 mm (2.6 in)
1903	59.4 mm (2.3 in)
1904	74.7 mm (2.9 in)
1905	53.9 mm (2.1 in)
1906	62.4 mm (2.5 in)
1907	59.4 mm (2.3 in)
1908	52.4 mm (2.1 in)
1909	53.6 mm (2.1 in)
1910	56.7 mm (2.2 in)
1911	40.1 mm (1.6 in)
1912	115.1 mm (4.5 in)
1913	43.0 mm (1.7 in)
1914	62.0 mm (2.4 in)
1915	72.5 mm (2.9 in)
1916	83.6 mm (3.3 in)
1917	104.9 mm (4.1 in)
1918	55.9 mm (2.2 in)
1919	71.7 mm (2.8 in)
1920	55.6 mm (2.2 in)
1921	113.3 mm (4.5 in)
1922	81.8 mm (3.2 in)
1923	65.3 mm (2.6 in)
1924	68.4 mm (2.7 in)
1925	67.9 mm (2.7 in)
1926	121.9 mm (4.8 in)
1927	109.7 mm (4.3 in)
1928	64.8 mm (2.6 in)
1929	62.9 mm (2.5 in)
1930	56.1 mm (2.2 in)
1931	35.6 mm (1.4 in)
1932	57.4 mm (2.3 in)
1933	56.7 mm (2.2 in)
1934	72.5 mm (2.9 in)
1935	77.5 mm (3.1 in)
1936	74.7 mm (2.9 in)
1937	65.3 mm (2.6 in)
1938	105.9 mm (4.2 in)
1939	49.0 mm (1.9 in)
1940	78.8 mm (3.1 in)
1941	56.1 mm (2.2 in)
1942	77.5 mm (3.1 in)
1943	70.2 mm (2.8 in)
1944	53.6 mm (2.1 in)
1945	78.4 mm (3.1 in)
1946	44.4 mm (1.7 in)
1947	69.4 mm (2.7 in)
1948	86.8 mm (3.4 in)
1949	69.1 mm (2.7 in)
1950	93.9 mm (3.7 in)
1951	81.1 mm (3.2 in)
1952	69.6 mm (2.7 in)
1953	98.5 mm (3.9 in)
1954	164.2 mm (6.5 in)
1955	55.7 mm (2.2 in)
1956	99.4 mm (3.9 in)
1957	98.0 mm (3.9 in)
1958	80.2 mm (3.2 in)
1959	61.7 mm (2.4 in)
1960	74.6 mm (2.9 in)
1961	73.9 mm (2.9 in)
1962	56.3 mm (2.2 in)
1963	38.4 mm (1.5 in)
1964	65.0 mm (2.6 in)
1965	66.3 mm (2.6 in)
1966	84.3 mm (3.3 in)
1967	82.3 mm (3.2 in)
1968	92.5 mm (3.6 in)
1969	46.5 mm (1.8 in)
1970	52.0 mm (2.0 in)
1971	73.2 mm (2.9 in)
1972	66.3 mm (2.6 in)
1973	73.3 mm (2.9 in)

Longest dry spell (CDD)

The longest dry spell of the year at Guelph Oac, 1881 to 1973. The record is 38 days in 1885, marked on the chart; the median year is 18 days.

Longest dry spell (CDD) at Guelph Oac by year
Year	Longest dry spell (CDD)
1881	19 days
1882	29 days
1883	22 days
1884	17 days
1885	38 days
1886	17 days
1887	17 days
1888	15 days
1889	24 days
1890	24 days
1891	19 days
1892	19 days
1893	18 days
1899	21 days
1900	26 days
1901	15 days
1902	19 days
1903	23 days
1904	29 days
1905	18 days
1906	17 days
1907	15 days
1908	25 days
1909	18 days
1910	34 days
1911	27 days
1912	35 days
1913	18 days
1914	16 days
1915	17 days
1916	29 days
1917	14 days
1918	16 days
1919	24 days
1920	16 days
1921	23 days
1922	22 days
1923	20 days
1924	35 days
1925	11 days
1926	13 days
1927	25 days
1928	17 days
1929	20 days
1930	12 days
1931	15 days
1932	17 days
1933	19 days
1934	18 days
1935	17 days
1936	22 days
1937	12 days
1938	12 days
1939	20 days
1940	12 days
1941	16 days
1942	17 days
1943	32 days
1944	17 days
1945	14 days
1946	16 days
1947	21 days
1948	19 days
1949	22 days
1950	15 days
1951	14 days
1952	13 days
1953	11 days
1954	19 days
1955	18 days
1956	19 days
1957	22 days
1958	22 days
1959	13 days
1960	14 days
1961	21 days
1962	24 days
1963	33 days
1964	18 days
1965	11 days
1966	20 days
1967	21 days
1968	13 days
1969	16 days
1970	16 days
1971	22 days
1972	13 days
1973	27 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

83 years with a frost

Across 83 years with a frost, the median last spring frost at Guelph Oac falls on 15 May and the median first autumn frost on 28 September, which leaves a median of 140 days between them.

In 1943 to 1972 the median growing season was 138 days. That is 4 days fewer than in 1882 to 1919.

Fitted over all years, the growing season changes by -0.4 days per decade at this station.

Frost dates and growing season at Guelph Oac
Measure	Median, all years	Earliest period (1882 to 1919)	Recent period (1943 to 1972)	Recent against earliest	Fitted trend
Last spring frost	15 May	15 May	14 May	1 day earlier	+0.2 days per decade
First autumn frost	28 September	28 September	28 September	no change	-0.2 days per decade
Growing days	140 days	142 days	138 days	4 days fewer	-0.4 days per decade

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.

Rainfall Return Levels

86 years, 1882 to 1973

A day with at least 43.2 mm (1.7 in) of rain is expected about once in 2 years. A day with at least 93.2 mm (3.7 in) of rain is expected about once in 100 years.

Rainfall return levels at Guelph Oac: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	43.2 mm (1.7 in)
5 years	55.2 mm (2.2 in)
10 years	63.7 mm (2.5 in)
25 years	75.0 mm (3.0 in)
50 years	83.9 mm (3.3 in)
100 years	93.2 mm (3.7 in)	Longer than the 86 years of record

The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 86 years of values from 1882 to 1973.

A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.

The largest wettest-day totals in the fit: 103.4 mm (4.1 in) in 1938; 95.8 mm (3.8 in) in 1954; 83.6 mm (3.3 in) in 1921.

Station Changes

1 suspected

One change was suspected in the annual mean temperature of Guelph Oac, at 1962. Each is measured against neighbouring stations.

Relative to 5 neighbouring stations, the station's annual mean temperature from 1962 ran 0.2 C (0.4 F) lower than in the years before (possible change).

Suspected changes in the annual mean temperature at Guelph Oac, against neighbouring stations
Year	Shift (C)	Shift (F)	Strength	Neighbours
1962	-0.2	-0.4	possible	5

Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.

Download the Data

Data for Guelph Oac standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Guelph Oac 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 2026-10-17 (17 October 2026). Records are computed by this site and are not official.

Data as of 2026-10-17. Last revised 17 October 2026 (2026-10-17).