Harrow Cda Weather Records (CA006133360)

Record envelope, standing records and threshold days for Harrow Cda (CA006133360), Ontario, Canada, with 77 years of record.

Key Facts for Harrow Cda

Harrow Cda (CA006133360) is a weather station in Ontario, Canada at 42.03 latitude and -82.90 longitude, 191 m (627 ft) above sea level.
The station reports from 1917 to 1993, 77 years of record.
1,464 records set at Harrow Cda still stand.
Records are tracked for tmax, tmin, prcp, snow: an element needs 30 years of data to be eligible.
Harrow Cda set a daily record low maximum temperature of -16.0 C (3.2 F) on 30 December 1983.

About the Station

Location: Ontario, Canada, 42.03 latitude, -82.90 longitude.
Elevation: 191 m (627 ft).
Period of record: 1917 to 1993, 77 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 Harrow Cda. 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 Harrow Cda, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	17.2 C (63.0 F)	-26.1 C (-15.0 F)	n/a	n/a
Feb	19.4 C (66.9 F)	-28.9 C (-20.0 F)	n/a	n/a
Mar	26.1 C (79.0 F)	-20.6 C (-5.1 F)	n/a	n/a
Apr	30.0 C (86.0 F)	-12.5 C (9.5 F)	n/a	n/a
May	33.9 C (93.0 F)	-3.9 C (25.0 F)	n/a	n/a
Jun	37.2 C (99.0 F)	1.7 C (35.1 F)	n/a	n/a
Jul	40.6 C (105.1 F)	5.6 C (42.1 F)	n/a	n/a
Aug	40.0 C (104.0 F)	3.9 C (39.0 F)	n/a	n/a
Sep	36.7 C (98.1 F)	-2.2 C (28.0 F)	n/a	n/a
Oct	32.2 C (90.0 F)	-6.1 C (21.0 F)	n/a	n/a
Nov	25.6 C (78.1 F)	-15.6 C (3.9 F)	n/a	n/a
Dec	17.2 C (63.0 F)	-27.0 C (-16.6 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Harrow Cda still stand. 1933 holds the most, with 40.

Standing records at Harrow Cda by the year they were set
Year set	Standing records
1917	30
1918	35
1919	13
1920	28
1921	28
1922	15
1923	26
1924	22
1925	32
1926	24
1927	24
1928	19
1929	28
1930	37
1931	28
1932	25
1933	40
1934	25
1935	23
1936	32
1937	16
1938	19
1939	20
1940	20
1941	20
1942	34
1943	17
1944	26
1945	35
1946	24
1947	19
1948	10
1949	25
1950	33
1951	28
1952	12
1953	21
1954	16
1955	13
1956	14
1957	15
1958	13
1959	19
1960	17
1961	8
1962	23
1963	29
1964	24
1965	24
1966	10
1967	27
1968	13
1969	13
1970	12
1971	10
1972	17
1973	12
1974	20
1975	19
1976	28
1977	30
1978	17
1979	28
1980	8
1981	16
1982	31
1983	25

All-Time Record Progression

6 new records

6 all-time records were set at Harrow Cda between 7 July 1957 and 24 December 1983. Each dot is a new record.

When Harrow Cda set new all-time records
Date	Kind	Detail
1957-07-07	Record daily precipitation	Record daily precipitation 74.4 mm (2.9 in)
1972-01-15	Record low maximum temperature	Record low maximum temperature -18.9 C (-2.0 F)
1974-12-01	Record daily snowfall	Record daily snowfall 39.4 cm (15.5 in)
1982-03-03	Record daily snowfall	Record daily snowfall 44.0 cm (17.3 in)
1983-05-01	Record daily precipitation	Record daily precipitation 88.5 mm (3.5 in)
1983-12-24	Record low maximum temperature	Record low maximum temperature -19.0 C (-2.2 F)

Wettest Day of Each Month

May: 88.5 mm (3.5 in)

The wettest day on record for each calendar month at Harrow Cda. The most was 88.5 mm (3.5 in) on 1 May 1983.

Record daily precipitation for each month at Harrow Cda
Month	Record daily precipitation (mm)	Date
Jan	44.5 mm (1.8 in)	26 January 1978
Feb	55.6 mm (2.2 in)	29 February 1976
Mar	44.0 mm (1.7 in)	3 March 1982
Apr	58.4 mm (2.3 in)	22 April 1977
May	88.5 mm (3.5 in)	1 May 1983
Jun	57.2 mm (2.3 in)	25 June 1968
Jul	74.4 mm (2.9 in)	7 July 1957
Aug	64.3 mm (2.5 in)	14 August 1972
Sep	57.7 mm (2.3 in)	23 September 1926
Oct	61.2 mm (2.4 in)	6 October 1959
Nov	56.3 mm (2.2 in)	1 November 1982
Dec	49.8 mm (2.0 in)	24 December 1965

Period of Record Coverage

1917 to 1983

67 years of record at Harrow Cda, 1917 to 1983. 1 years have data for under 90 percent of days and are left out of rankings: 1917.

Days with data per year at Harrow Cda
Year	Days with data	Share of year	Complete
1917	270	74%	No
1918	365	100%	Yes
1919	365	100%	Yes
1920	365	100%	Yes
1921	365	100%	Yes
1922	365	100%	Yes
1923	365	100%	Yes
1924	366	100%	Yes
1925	365	100%	Yes
1926	365	100%	Yes
1927	364	100%	Yes
1928	366	100%	Yes
1929	365	100%	Yes
1930	365	100%	Yes
1931	365	100%	Yes
1932	366	100%	Yes
1933	365	100%	Yes
1934	365	100%	Yes
1935	365	100%	Yes
1936	366	100%	Yes
1937	365	100%	Yes
1938	365	100%	Yes
1939	365	100%	Yes
1940	366	100%	Yes
1941	365	100%	Yes
1942	365	100%	Yes
1943	365	100%	Yes
1944	366	100%	Yes
1945	365	100%	Yes
1946	365	100%	Yes
1947	365	100%	Yes
1948	366	100%	Yes
1949	365	100%	Yes
1950	365	100%	Yes
1951	365	100%	Yes
1952	366	100%	Yes
1953	365	100%	Yes
1954	365	100%	Yes
1955	365	100%	Yes
1956	366	100%	Yes
1957	365	100%	Yes
1958	365	100%	Yes
1959	365	100%	Yes
1960	366	100%	Yes
1961	365	100%	Yes
1962	365	100%	Yes
1963	365	100%	Yes
1964	366	100%	Yes
1965	365	100%	Yes
1966	364	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	365	100%	Yes
1978	365	100%	Yes
1979	365	100%	Yes
1980	366	100%	Yes
1981	360	99%	Yes
1982	363	99%	Yes
1983	363	99%	Yes

Latest Records

Latest records at Harrow Cda
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
30 December 1983	Harrow Cda, CA	daily low max	-16.0 C (3.2 F)	5.4 C (9.7 F)	65 years	35 of 100 (Notable)
30 December 1983	Harrow Cda, CA	monthly low min	-27.0 C (-16.6 F)	3.0 C (5.4 F)	0 years	21 of 100 (Routine)
26 December 1983	Harrow Cda, CA	daily low min	-21.5 C (-6.7 F)	2.6 C (4.7 F)	58 years	27 of 100 (Routine)
25 December 1983	Harrow Cda, CA	daily low max	-17.5 C (0.5 F)	3.1 C (5.6 F)	58 years	29 of 100 (Routine)
25 December 1983	Harrow Cda, CA	monthly low min	-24.0 C (-11.2 F)	0.5 C (0.9 F)	0 years	16 of 100 (Routine)
24 December 1983	Harrow Cda, CA	monthly low min	-23.5 C (-10.3 F)	0.7 C (1.3 F)	66 years	36 of 100 (Notable)
24 December 1983	Harrow Cda, CA	all-time low max	-19.0 C (-2.2 F)	0.1 C (0.2 F)	11 years	29 of 100 (Routine)
23 December 1983	Harrow Cda, CA	daily low max	-14.0 C (6.8 F)	3.4 C (6.1 F)	37 years	23 of 100 (Routine)
5 December 1983	Harrow Cda, CA	daily rain	27.0 mm (1.1 in)	9.5 mm (0.37 in)	10 years	23 of 100 (Routine)
13 November 1983	Harrow Cda, CA	daily low min	-7.5 C (18.5 F)	1.4 C (2.5 F)	56 years	24 of 100 (Routine)
10 November 1983	Harrow Cda, CA	daily rain	25.6 mm (1.0 in)	5.8 mm (0.23 in)	53 years	30 of 100 (Routine)
12 October 1983	Harrow Cda, CA	daily rain	23.9 mm (0.9 in)	11.2 mm (0.4 in)	12 years	20 of 100 (Routine)
4 October 1983	Harrow Cda, CA	daily high min	19.0 C (66.2 F)	0.1 C (0.2 F)	32 years	15 of 100 (Routine)
10 September 1983	Harrow Cda, CA	daily high max	33.0 C (91.4 F)	0.8 C (1.4 F)	52 years	22 of 100 (Routine)
6 September 1983	Harrow Cda, CA	daily high min	22.5 C (72.5 F)	0.3 C (0.5 F)	60 years	24 of 100 (Routine)
20 August 1983	Harrow Cda, CA	daily high min	25.5 C (77.9 F)	2.7 C (4.9 F)	14 years	16 of 100 (Routine)
10 August 1983	Harrow Cda, CA	daily rain	29.8 mm (1.2 in)	3.4 mm (0.13 in)	12 years	12 of 100 (Routine)
16 July 1983	Harrow Cda, CA	daily high max	34.0 C (93.2 F)	1.2 C (2.2 F)	38 years	20 of 100 (Routine)
15 July 1983	Harrow Cda, CA	daily high max	34.0 C (93.2 F)	0.9 C (1.6 F)	5 years	9 of 100 (Routine)
6 July 1983	Harrow Cda, CA	daily low max	21.5 C (70.7 F)	0.2 C (0.4 F)	13 years	10 of 100 (Routine)

Climate Trend

65 complete years, 1918 to 1983

One stripe for each of 65 complete years at Harrow Cda, 1918 to 1983. Blue stripes are years cooler than the station's own mean of 9.3 C (48.8 F); red stripes are warmer. The coolest year was 1978, at 8.0 C (46.3 F), and the warmest was 1946, at 11.0 C (51.8 F). The strongest colour marks a difference of 1.7 C (3.1 F).

Annual mean temperature at Harrow Cda as warming stripes, 1918 to 1983
Year	Annual mean temperature	Difference from the station mean
1918	9.1 C	-0.26 C
1919	9.6 C	+0.27 C
1920	8.4 C	-0.97 C
1921	11.0 C	+1.69 C
1922	9.8 C	+0.44 C
1923	9.1 C	-0.26 C
1924	8.1 C	-1.22 C
1925	8.8 C	-0.56 C
1926	8.1 C	-1.23 C
1927	9.3 C	-0.02 C
1928	9.3 C	+0.01 C
1929	8.4 C	-0.94 C
1930	9.5 C	+0.18 C
1931	11.0 C	+1.64 C
1932	9.9 C	+0.56 C
1933	10.3 C	+1.02 C
1934	9.5 C	+0.18 C
1935	8.9 C	-0.41 C
1936	9.0 C	-0.37 C
1937	9.0 C	-0.31 C
1938	10.3 C	+0.98 C
1939	10.3 C	+1.00 C
1940	8.8 C	-0.56 C
1941	10.6 C	+1.29 C
1942	9.9 C	+0.53 C
1943	9.3 C	-0.06 C
1944	10.3 C	+1.02 C
1945	9.5 C	+0.18 C
1946	11.0 C	+1.70 C
1947	9.9 C	+0.60 C
1948	9.8 C	+0.43 C
1949	10.8 C	+1.51 C
1950	8.9 C	-0.44 C
1951	9.3 C	-0.05 C
1952	10.4 C	+1.05 C
1953	10.8 C	+1.43 C
1954	9.9 C	+0.60 C
1955	10.0 C	+0.72 C
1956	9.0 C	-0.31 C
1958	8.3 C	-1.07 C
1959	9.1 C	-0.23 C
1960	8.7 C	-0.64 C
1961	9.3 C	-0.05 C
1962	8.9 C	-0.41 C
1963	8.4 C	-0.96 C
1964	9.5 C	+0.13 C
1965	9.0 C	-0.35 C
1966	8.8 C	-0.56 C
1967	8.8 C	-0.51 C
1968	9.3 C	-0.06 C
1969	8.7 C	-0.61 C
1970	8.9 C	-0.39 C
1971	9.5 C	+0.22 C
1972	8.5 C	-0.85 C
1973	10.2 C	+0.85 C
1974	9.1 C	-0.23 C
1975	9.7 C	+0.36 C
1976	8.5 C	-0.85 C
1977	8.9 C	-0.39 C
1978	8.0 C	-1.36 C
1979	8.2 C	-1.15 C
1980	8.4 C	-0.92 C
1981	8.8 C	-0.48 C
1982	8.9 C	-0.47 C
1983	9.5 C	+0.22 C

The annual mean temperature here has fallen by 0.10 C (0.00 to 0.20) per decade over 1918 to 1983. In Fahrenheit: 0.18 F (0.00 to 0.36) per decade. The slope is a straight line fitted to 65 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Harrow Cda
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	-0.10 C (-0.20 to 0.00) per decade	-0.18 F (-0.36 to 0.00) per decade	1918 to 1983	65	Fall
Mean daily maximum	-0.3 C (-0.4 to -0.2) per decade	-0.5 F (-0.7 to -0.3) per decade	1918 to 1983	65	Fall
Mean daily minimum	0.08 C (-0.02 to 0.17) per decade	0.14 F (-0.03 to 0.31) per decade	1918 to 1983	65	Not clearly different from zero

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

1917 to 1983

Yearly extremes at Harrow Cda: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	40.6 C (105.1 F)	1936	34.4 C (93.9 F)	67
Coldest night (TNn)	-28.9 C (-20.0 F)	1918	-20.6 C (-5.1 F)	67
Wettest day (Rx1day)	88.5 mm (3.5 in)	1983	42.7 mm (1.7 in)	67
Wettest five days (Rx5day)	148.9 mm (5.9 in)	1957	63.4 mm (2.5 in)	67
Longest dry spell (CDD)	35 days	1924	19 days	67

Hottest day (TXx)

The hottest day of the year at Harrow Cda, 1917 to 1983. The record is 40.6 C (105.1 F) in 1936, marked on the chart; the median year is 34.4 C (93.9 F).

Hottest day (TXx) at Harrow Cda by year
Year	Hottest day (TXx)
1917	35.6 C (96.1 F)
1918	40.0 C (104.0 F)
1919	35.6 C (96.1 F)
1920	33.3 C (91.9 F)
1921	36.1 C (97.0 F)
1922	34.4 C (93.9 F)
1923	35.0 C (95.0 F)
1924	34.4 C (93.9 F)
1925	36.7 C (98.1 F)
1926	37.2 C (99.0 F)
1927	36.7 C (98.1 F)
1928	34.4 C (93.9 F)
1929	33.9 C (93.0 F)
1930	37.2 C (99.0 F)
1931	36.7 C (98.1 F)
1932	36.7 C (98.1 F)
1933	37.2 C (99.0 F)
1934	37.2 C (99.0 F)
1935	37.2 C (99.0 F)
1936	40.6 C (105.1 F)
1937	33.9 C (93.0 F)
1938	33.3 C (91.9 F)
1939	35.0 C (95.0 F)
1940	35.6 C (96.1 F)
1941	35.6 C (96.1 F)
1942	36.1 C (97.0 F)
1943	35.6 C (96.1 F)
1944	37.2 C (99.0 F)
1945	34.4 C (93.9 F)
1946	37.8 C (100.0 F)
1947	36.1 C (97.0 F)
1948	35.6 C (96.1 F)
1949	35.6 C (96.1 F)
1950	34.4 C (93.9 F)
1951	33.9 C (93.0 F)
1952	37.2 C (99.0 F)
1953	37.2 C (99.0 F)
1954	36.1 C (97.0 F)
1955	36.1 C (97.0 F)
1956	32.8 C (91.0 F)
1957	31.7 C (89.1 F)
1958	31.7 C (89.1 F)
1959	32.2 C (90.0 F)
1960	33.9 C (93.0 F)
1961	32.8 C (91.0 F)
1962	33.9 C (93.0 F)
1963	33.9 C (93.0 F)
1964	33.9 C (93.0 F)
1965	33.3 C (91.9 F)
1966	35.0 C (95.0 F)
1967	33.9 C (93.0 F)
1968	32.8 C (91.0 F)
1969	32.2 C (90.0 F)
1970	33.3 C (91.9 F)
1971	35.0 C (95.0 F)
1972	32.8 C (91.0 F)
1973	34.4 C (93.9 F)
1974	33.9 C (93.0 F)
1975	33.3 C (91.9 F)
1976	33.9 C (93.0 F)
1977	33.1 C (91.6 F)
1978	35.0 C (95.0 F)
1979	31.0 C (87.8 F)
1980	33.0 C (91.4 F)
1981	33.0 C (91.4 F)
1982	32.0 C (89.6 F)
1983	34.5 C (94.1 F)

Coldest night (TNn)

The coldest night of the year at Harrow Cda, 1917 to 1983. The record is -28.9 C (-20.0 F) in 1918, marked on the chart; the median year is -20.6 C (-5.1 F).

Coldest night (TNn) at Harrow Cda by year
Year	Coldest night (TNn)
1917	-22.8 C (-9.0 F)
1918	-28.9 C (-20.0 F)
1919	-18.3 C (-0.9 F)
1920	-23.3 C (-9.9 F)
1921	-14.4 C (6.1 F)
1922	-21.1 C (-6.0 F)
1923	-18.9 C (-2.0 F)
1924	-23.9 C (-11.0 F)
1925	-23.3 C (-9.9 F)
1926	-19.4 C (-2.9 F)
1927	-25.6 C (-14.1 F)
1928	-18.3 C (-0.9 F)
1929	-24.4 C (-11.9 F)
1930	-24.4 C (-11.9 F)
1931	-16.1 C (3.0 F)
1932	-20.6 C (-5.1 F)
1933	-22.8 C (-9.0 F)
1934	-27.2 C (-17.0 F)
1935	-20.0 C (-4.0 F)
1936	-22.2 C (-8.0 F)
1937	-19.4 C (-2.9 F)
1938	-18.9 C (-2.0 F)
1939	-19.4 C (-2.9 F)
1940	-23.3 C (-9.9 F)
1941	-15.6 C (3.9 F)
1942	-20.6 C (-5.1 F)
1943	-20.6 C (-5.1 F)
1944	-21.7 C (-7.1 F)
1945	-21.1 C (-6.0 F)
1946	-16.7 C (1.9 F)
1947	-16.7 C (1.9 F)
1948	-23.3 C (-9.9 F)
1949	-13.9 C (7.0 F)
1950	-20.0 C (-4.0 F)
1951	-21.1 C (-6.0 F)
1952	-13.3 C (8.1 F)
1953	-14.4 C (6.1 F)
1954	-17.2 C (1.0 F)
1955	-16.7 C (1.9 F)
1956	-16.7 C (1.9 F)
1957	-21.1 C (-6.0 F)
1958	-22.2 C (-8.0 F)
1959	-18.9 C (-2.0 F)
1960	-20.0 C (-4.0 F)
1961	-23.3 C (-9.9 F)
1962	-22.2 C (-8.0 F)
1963	-26.1 C (-15.0 F)
1964	-17.8 C (0.0 F)
1965	-21.7 C (-7.1 F)
1966	-20.6 C (-5.1 F)
1967	-18.3 C (-0.9 F)
1968	-21.1 C (-6.0 F)
1969	-18.9 C (-2.0 F)
1970	-22.8 C (-9.0 F)
1971	-20.6 C (-5.1 F)
1972	-23.3 C (-9.9 F)
1973	-18.9 C (-2.0 F)
1974	-19.4 C (-2.9 F)
1975	-20.0 C (-4.0 F)
1976	-22.2 C (-8.0 F)
1977	-23.3 C (-9.9 F)
1978	-20.0 C (-4.0 F)
1979	-23.5 C (-10.3 F)
1980	-18.5 C (-1.3 F)
1981	-24.5 C (-12.1 F)
1982	-26.0 C (-14.8 F)
1983	-27.0 C (-16.6 F)

Wettest day (Rx1day)

The wettest day of the year at Harrow Cda, 1917 to 1983. The record is 88.5 mm (3.5 in) in 1983, marked on the chart; the median year is 42.7 mm (1.7 in).

Wettest day (Rx1day) at Harrow Cda by year
Year	Wettest day (Rx1day)
1917	46.0 mm (1.8 in)
1918	38.9 mm (1.5 in)
1919	44.2 mm (1.7 in)
1920	47.2 mm (1.9 in)
1921	50.8 mm (2.0 in)
1922	35.1 mm (1.4 in)
1923	37.1 mm (1.5 in)
1924	34.3 mm (1.4 in)
1925	27.2 mm (1.1 in)
1926	57.7 mm (2.3 in)
1927	28.2 mm (1.1 in)
1928	26.9 mm (1.1 in)
1929	38.1 mm (1.5 in)
1930	19.6 mm (0.8 in)
1931	23.6 mm (0.9 in)
1932	34.8 mm (1.4 in)
1933	16.5 mm (0.6 in)
1934	43.7 mm (1.7 in)
1935	36.1 mm (1.4 in)
1936	36.1 mm (1.4 in)
1937	56.9 mm (2.2 in)
1938	37.8 mm (1.5 in)
1939	53.6 mm (2.1 in)
1940	41.4 mm (1.6 in)
1941	39.6 mm (1.6 in)
1942	42.7 mm (1.7 in)
1943	32.8 mm (1.3 in)
1944	34.3 mm (1.4 in)
1945	49.0 mm (1.9 in)
1946	33.3 mm (1.3 in)
1947	49.0 mm (1.9 in)
1948	36.6 mm (1.4 in)
1949	40.6 mm (1.6 in)
1950	30.5 mm (1.2 in)
1951	47.2 mm (1.9 in)
1952	53.6 mm (2.1 in)
1953	37.8 mm (1.5 in)
1954	57.7 mm (2.3 in)
1955	38.6 mm (1.5 in)
1956	42.7 mm (1.7 in)
1957	74.4 mm (2.9 in)
1958	28.7 mm (1.1 in)
1959	61.2 mm (2.4 in)
1960	32.8 mm (1.3 in)
1961	41.1 mm (1.6 in)
1962	56.1 mm (2.2 in)
1963	34.3 mm (1.4 in)
1964	47.5 mm (1.9 in)
1965	49.8 mm (2.0 in)
1966	71.6 mm (2.8 in)
1967	48.5 mm (1.9 in)
1968	57.2 mm (2.3 in)
1969	68.8 mm (2.7 in)
1970	46.7 mm (1.8 in)
1971	36.3 mm (1.4 in)
1972	64.3 mm (2.5 in)
1973	50.8 mm (2.0 in)
1974	39.4 mm (1.6 in)
1975	46.0 mm (1.8 in)
1976	55.6 mm (2.2 in)
1977	58.4 mm (2.3 in)
1978	44.5 mm (1.8 in)
1979	38.5 mm (1.5 in)
1980	40.0 mm (1.6 in)
1981	45.8 mm (1.8 in)
1982	56.3 mm (2.2 in)
1983	88.5 mm (3.5 in)

Wettest five days (Rx5day)

The wettest five days of the year at Harrow Cda, 1917 to 1983. The record is 148.9 mm (5.9 in) in 1957, marked on the chart; the median year is 63.4 mm (2.5 in).

Wettest five days (Rx5day) at Harrow Cda by year
Year	Wettest five days (Rx5day)
1917	72.9 mm (2.9 in)
1918	56.2 mm (2.2 in)
1919	55.7 mm (2.2 in)
1920	86.3 mm (3.4 in)
1921	56.4 mm (2.2 in)
1922	51.8 mm (2.0 in)
1923	43.7 mm (1.7 in)
1924	51.1 mm (2.0 in)
1925	52.6 mm (2.1 in)
1926	81.5 mm (3.2 in)
1927	42.0 mm (1.7 in)
1928	40.4 mm (1.6 in)
1929	52.3 mm (2.1 in)
1930	33.9 mm (1.3 in)
1931	34.5 mm (1.4 in)
1932	65.3 mm (2.6 in)
1933	31.2 mm (1.2 in)
1934	46.5 mm (1.8 in)
1935	62.5 mm (2.5 in)
1936	50.1 mm (2.0 in)
1937	76.7 mm (3.0 in)
1938	85.3 mm (3.4 in)
1939	99.6 mm (3.9 in)
1940	71.6 mm (2.8 in)
1941	57.7 mm (2.3 in)
1942	77.4 mm (3.0 in)
1943	51.6 mm (2.0 in)
1944	40.6 mm (1.6 in)
1945	81.7 mm (3.2 in)
1946	45.8 mm (1.8 in)
1947	86.5 mm (3.4 in)
1948	80.0 mm (3.1 in)
1949	62.7 mm (2.5 in)
1950	56.1 mm (2.2 in)
1951	48.8 mm (1.9 in)
1952	63.4 mm (2.5 in)
1953	42.7 mm (1.7 in)
1954	76.3 mm (3.0 in)
1955	62.5 mm (2.5 in)
1956	64.3 mm (2.5 in)
1957	148.9 mm (5.9 in)
1958	50.9 mm (2.0 in)
1959	93.8 mm (3.7 in)
1960	59.1 mm (2.3 in)
1961	87.0 mm (3.4 in)
1962	64.7 mm (2.5 in)
1963	52.1 mm (2.1 in)
1964	72.4 mm (2.9 in)
1965	62.8 mm (2.5 in)
1966	133.4 mm (5.3 in)
1967	61.2 mm (2.4 in)
1968	103.9 mm (4.1 in)
1969	111.2 mm (4.4 in)
1970	53.3 mm (2.1 in)
1971	47.3 mm (1.9 in)
1972	121.7 mm (4.8 in)
1973	66.8 mm (2.6 in)
1974	63.0 mm (2.5 in)
1975	80.1 mm (3.2 in)
1976	116.6 mm (4.6 in)
1977	102.5 mm (4.0 in)
1978	64.3 mm (2.5 in)
1979	69.8 mm (2.7 in)
1980	75.3 mm (3.0 in)
1981	69.4 mm (2.7 in)
1982	82.7 mm (3.3 in)
1983	127.9 mm (5.0 in)

Longest dry spell (CDD)

The longest dry spell of the year at Harrow Cda, 1917 to 1983. The record is 35 days in 1924, marked on the chart; the median year is 19 days.

Longest dry spell (CDD) at Harrow Cda by year
Year	Longest dry spell (CDD)
1917	27 days
1918	24 days
1919	26 days
1920	23 days
1921	19 days
1922	27 days
1923	22 days
1924	35 days
1925	23 days
1926	15 days
1927	21 days
1928	19 days
1929	19 days
1930	27 days
1931	19 days
1932	19 days
1933	21 days
1934	20 days
1935	14 days
1936	21 days
1937	15 days
1938	15 days
1939	19 days
1940	12 days
1941	22 days
1942	22 days
1943	18 days
1944	35 days
1945	23 days
1946	18 days
1947	24 days
1948	18 days
1949	21 days
1950	13 days
1951	15 days
1952	21 days
1953	22 days
1954	15 days
1955	17 days
1956	20 days
1957	23 days
1958	15 days
1959	12 days
1960	17 days
1961	23 days
1962	14 days
1963	31 days
1964	21 days
1965	16 days
1966	16 days
1967	17 days
1968	18 days
1969	35 days
1970	17 days
1971	16 days
1972	14 days
1973	17 days
1974	14 days
1975	15 days
1976	27 days
1977	13 days
1978	25 days
1979	16 days
1980	15 days
1981	16 days
1982	11 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

65 years with a frost

Across 65 years with a frost, the median last spring frost at Harrow Cda falls on 3 May and the median first autumn frost on 15 October, which leaves a median of 166 days between them.

In 1953 to 1983 the median growing season was 168 days. That is 5 days more than in 1918 to 1947.

Fitted over all years, the growing season changes by +1.9 days per decade at this station.

Frost dates and growing season at Harrow Cda
Measure	Median, all years	Earliest period (1918 to 1947)	Recent period (1953 to 1983)	Recent against earliest	Fitted trend
Last spring frost	3 May	11 May	29 April	12 days earlier	-1.8 days per decade
First autumn frost	15 October	13 October	16 October	3 days later	+0.1 days per decade
Growing days	166 days	163 days	168 days	5 days more	+1.9 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

65 years, 1918 to 1983

A day with at least 42.8 mm (1.7 in) of rain is expected about once in 2 years. A day with at least 81.8 mm (3.2 in) of rain is expected about once in 100 years.

Rainfall return levels at Harrow Cda: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	42.8 mm (1.7 in)
5 years	54.5 mm (2.1 in)
10 years	61.7 mm (2.4 in)
25 years	70.2 mm (2.8 in)
50 years	76.2 mm (3.0 in)
100 years	81.8 mm (3.2 in)	Longer than the 65 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, 65 years of values from 1918 to 1983.

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: 88.5 mm (3.5 in) in 1983; 74.4 mm (2.9 in) in 1957; 71.6 mm (2.8 in) in 1966.

Station Changes

No change in the annual mean temperature of this station was found against its neighbours.

Download the Data

Data for Harrow Cda standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Harrow Cda 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).