Record highRecord low2026 daily maximum2026 daily minimum
The band shows the record high and record low for each calendar day at Ottawa. 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 Ottawa, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
15.6 C (60.1 F)
-36.1 C (-33.0 F)
n/a
n/a
Feb
12.2 C (54.0 F)
-36.1 C (-33.0 F)
n/a
n/a
Mar
21.7 C (71.1 F)
-35.6 C (-32.1 F)
n/a
n/a
Apr
30.0 C (86.0 F)
-19.4 C (-2.9 F)
n/a
n/a
May
33.9 C (93.0 F)
-6.1 C (21.0 F)
n/a
n/a
Jun
36.1 C (97.0 F)
1.7 C (35.1 F)
n/a
n/a
Jul
38.3 C (100.9 F)
5.0 C (41.0 F)
n/a
n/a
Aug
37.2 C (99.0 F)
1.1 C (34.0 F)
n/a
n/a
Sep
38.9 C (102.0 F)
-1.7 C (28.9 F)
n/a
n/a
Oct
30.6 C (87.1 F)
-9.4 C (15.1 F)
n/a
n/a
Nov
20.6 C (69.1 F)
-30.6 C (-23.1 F)
n/a
n/a
Dec
12.8 C (55.0 F)
-36.7 C (-34.1 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Ottawa still stand. 1885 holds the most, with 59.
Standing records at Ottawa by the year they were set
Year set
Standing records
1872
21
1873
28
1874
26
1875
46
1876
48
1877
6
1878
3
1879
51
1880
36
1881
9
1882
3
1883
31
1884
49
1885
59
1886
42
1887
41
1888
34
1889
30
1890
3
1899
11
1900
31
1901
21
1902
22
1903
31
1904
16
1905
11
1906
31
1907
21
1908
17
1909
16
1910
25
1911
31
1912
20
1913
33
1914
34
1915
30
1916
26
1917
21
1918
38
1919
28
1920
25
1921
27
1922
25
1923
28
1924
18
1925
31
1926
15
1927
17
1928
16
1929
20
1930
40
1931
36
1932
24
1933
32
1934
28
1935
2
All-Time Record Progression
4 new records
4 all-time records were set at Ottawa between 2 July 1931 and 29 December 1933. Each dot is a new record.
When Ottawa set new all-time records
Date
Kind
Detail
1931-07-02
Record high maximum temperature
Record high maximum temperature 38.3 C (100.9 F)
1931-09-11
Record high maximum temperature
Record high maximum temperature 38.9 C (102.0 F)
1933-12-29
Record low maximum temperature
Record low maximum temperature -27.8 C (-18.0 F)
1933-12-29
Record low minimum temperature
Record low minimum temperature -36.7 C (-34.1 F)
Wettest Day of Each Month
Oct: 94.0 mm (3.7 in)
The wettest day on record for each calendar month at Ottawa. The most was 94.0 mm (3.7 in) on 4 October 1887.
Record daily precipitation for each month at Ottawa
Month
Record daily precipitation (mm)
Date
Jan
48.8 mm (1.9 in)
7 January 1905
Feb
50.8 mm (2.0 in)
15 February 1876
Mar
71.1 mm (2.8 in)
18 March 1881
Apr
50.8 mm (2.0 in)
6 April 1885
May
53.3 mm (2.1 in)
17 May 1916
Jun
53.8 mm (2.1 in)
28 June 1928
Jul
57.4 mm (2.3 in)
17 July 1900
Aug
71.1 mm (2.8 in)
11 August 1887
Sep
61.7 mm (2.4 in)
5 September 1918
Oct
94.0 mm (3.7 in)
4 October 1887
Nov
54.1 mm (2.1 in)
25 November 1912
Dec
38.6 mm (1.5 in)
10 December 1878
Period of Record Coverage
1872 to 1935
Complete yearUnder 90 percent of days
56 years of record at Ottawa, 1872 to 1935. 8 years have data for under 90 percent of days and are left out of rankings: 1872, 1877, 1878, 1881, 1882, 1890, 1899, 1935.
Cooler than the station meanWarmer than the station mean
One stripe for each of 47 complete years at Ottawa, 1873 to 1934. Blue stripes are years cooler than the station's own mean of 5.5 C (41.9 F); red stripes are warmer. The coolest year was 1885, at 3.1 C (37.5 F), and the warmest was 1931, at 8.1 C (46.6 F). The strongest colour marks a difference of 2.7 C (4.9 F).
Annual mean temperature at Ottawa as warming stripes, 1873 to 1934
Year
Annual mean temperature
Difference from the station mean
1873
5.2 C
-0.37 C
1874
5.3 C
-0.23 C
1875
3.4 C
-2.11 C
1876
5.3 C
-0.18 C
1880
6.5 C
+0.98 C
1883
3.5 C
-2.00 C
1884
4.4 C
-1.13 C
1885
3.1 C
-2.45 C
1886
4.1 C
-1.43 C
1887
4.4 C
-1.16 C
1888
4.3 C
-1.21 C
1889
5.8 C
+0.29 C
1900
6.2 C
+0.64 C
1901
6.0 C
+0.51 C
1902
5.9 C
+0.41 C
1903
6.0 C
+0.46 C
1904
4.0 C
-1.55 C
1905
5.3 C
-0.19 C
1906
6.3 C
+0.77 C
1907
4.9 C
-0.66 C
1908
5.7 C
+0.21 C
1909
5.2 C
-0.30 C
1910
5.8 C
+0.32 C
1911
5.7 C
+0.20 C
1912
4.5 C
-1.00 C
1913
6.4 C
+0.89 C
1914
4.7 C
-0.81 C
1915
6.5 C
+1.00 C
1916
5.6 C
+0.07 C
1917
3.9 C
-1.61 C
1918
5.5 C
+0.01 C
1919
6.5 C
+0.95 C
1920
5.9 C
+0.42 C
1921
7.4 C
+1.83 C
1922
6.6 C
+1.04 C
1923
5.4 C
-0.09 C
1924
5.6 C
+0.11 C
1925
5.7 C
+0.21 C
1926
4.6 C
-0.88 C
1927
6.4 C
+0.92 C
1928
6.0 C
+0.45 C
1929
6.0 C
+0.45 C
1930
6.9 C
+1.35 C
1931
8.1 C
+2.61 C
1932
6.9 C
+1.39 C
1933
6.4 C
+0.90 C
1934
5.4 C
-0.11 C
The annual mean temperature here has risen by 0.3 C (0.2 to 0.5) per decade over 1873 to 1934. In Fahrenheit: 0.6 F (0.3 to 0.8) per decade. The slope is a straight line fitted to 47 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Ottawa
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.3 C (0.2 to 0.5) per decade
0.6 F (0.3 to 0.8) per decade
1873 to 1934
47
Rise
Mean daily maximum
0.3 C (0.1 to 0.4) per decade
0.5 F (0.2 to 0.8) per decade
1873 to 1934
47
Rise
Mean daily minimum
0.4 C (0.2 to 0.5) per decade
0.7 F (0.4 to 0.9) per decade
1873 to 1934
47
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
1872 to 1935
Yearly extremes at Ottawa: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
38.9 C (102.0 F)
1931
33.9 C (93.0 F)
56
Coldest night (TNn)
-36.7 C (-34.1 F)
1933
-30.8 C (-23.5 F)
56
Wettest day (Rx1day)
94.0 mm (3.7 in)
1887
39.9 mm (1.6 in)
55
Wettest five days (Rx5day)
158.8 mm (6.3 in)
1885
63.8 mm (2.5 in)
55
Longest dry spell (CDD)
36 days
1881
15 days
55
Hottest day (TXx)
The hottest day of the year at Ottawa, 1872 to 1935. The record is 38.9 C (102.0 F) in 1931, marked on the chart; the median year is 33.9 C (93.0 F).
Hottest day (TXx) at Ottawa by year
Year
Hottest day (TXx)
1872
34.4 C (93.9 F)
1873
35.0 C (95.0 F)
1874
34.4 C (93.9 F)
1875
32.2 C (90.0 F)
1876
37.2 C (99.0 F)
1877
10.6 C (51.1 F)
1878
24.4 C (75.9 F)
1879
35.6 C (96.1 F)
1880
33.9 C (93.0 F)
1881
31.7 C (89.1 F)
1882
26.1 C (79.0 F)
1883
29.4 C (84.9 F)
1884
34.4 C (93.9 F)
1885
31.1 C (88.0 F)
1886
31.7 C (89.1 F)
1887
34.4 C (93.9 F)
1888
35.0 C (95.0 F)
1889
33.3 C (91.9 F)
1890
10.0 C (50.0 F)
1899
33.3 C (91.9 F)
1900
31.7 C (89.1 F)
1901
36.7 C (98.1 F)
1902
32.2 C (90.0 F)
1903
32.2 C (90.0 F)
1904
34.4 C (93.9 F)
1905
32.2 C (90.0 F)
1906
35.0 C (95.0 F)
1907
34.4 C (93.9 F)
1908
34.4 C (93.9 F)
1909
30.6 C (87.1 F)
1910
31.1 C (88.0 F)
1911
35.0 C (95.0 F)
1912
32.8 C (91.0 F)
1913
33.9 C (93.0 F)
1914
31.1 C (88.0 F)
1915
31.1 C (88.0 F)
1916
36.1 C (97.0 F)
1917
36.7 C (98.1 F)
1918
34.4 C (93.9 F)
1919
36.1 C (97.0 F)
1920
33.9 C (93.0 F)
1921
36.7 C (98.1 F)
1922
33.9 C (93.0 F)
1923
35.0 C (95.0 F)
1924
32.8 C (91.0 F)
1925
36.1 C (97.0 F)
1926
31.1 C (88.0 F)
1927
30.6 C (87.1 F)
1928
33.3 C (91.9 F)
1929
36.1 C (97.0 F)
1930
33.3 C (91.9 F)
1931
38.9 C (102.0 F)
1932
33.3 C (91.9 F)
1933
36.1 C (97.0 F)
1934
34.4 C (93.9 F)
1935
11.7 C (53.1 F)
Coldest night (TNn)
The coldest night of the year at Ottawa, 1872 to 1935. The record is -36.7 C (-34.1 F) in 1933, marked on the chart; the median year is -30.8 C (-23.5 F).
Coldest night (TNn) at Ottawa by year
Year
Coldest night (TNn)
1872
-33.9 C (-29.0 F)
1873
-31.7 C (-25.1 F)
1874
-30.6 C (-23.1 F)
1875
-35.0 C (-31.0 F)
1876
-34.4 C (-29.9 F)
1877
-31.7 C (-25.1 F)
1878
-22.2 C (-8.0 F)
1879
-31.7 C (-25.1 F)
1880
-29.4 C (-20.9 F)
1881
-28.3 C (-18.9 F)
1882
-23.3 C (-9.9 F)
1883
-33.9 C (-29.0 F)
1884
-36.1 C (-33.0 F)
1885
-32.8 C (-27.0 F)
1886
-32.8 C (-27.0 F)
1887
-35.6 C (-32.1 F)
1888
-36.1 C (-33.0 F)
1889
-35.6 C (-32.1 F)
1890
-28.9 C (-20.0 F)
1899
-26.1 C (-15.0 F)
1900
-31.1 C (-24.0 F)
1901
-31.1 C (-24.0 F)
1902
-28.9 C (-20.0 F)
1903
-30.0 C (-22.0 F)
1904
-34.4 C (-29.9 F)
1905
-26.1 C (-15.0 F)
1906
-28.9 C (-20.0 F)
1907
-28.9 C (-20.0 F)
1908
-30.6 C (-23.1 F)
1909
-26.7 C (-16.1 F)
1910
-31.7 C (-25.1 F)
1911
-28.9 C (-20.0 F)
1912
-32.8 C (-27.0 F)
1913
-27.8 C (-18.0 F)
1914
-34.4 C (-29.9 F)
1915
-31.1 C (-24.0 F)
1916
-28.9 C (-20.0 F)
1917
-35.0 C (-31.0 F)
1918
-32.8 C (-27.0 F)
1919
-28.9 C (-20.0 F)
1920
-33.9 C (-29.0 F)
1921
-30.6 C (-23.1 F)
1922
-29.4 C (-20.9 F)
1923
-35.0 C (-31.0 F)
1924
-33.3 C (-27.9 F)
1925
-33.9 C (-29.0 F)
1926
-30.6 C (-23.1 F)
1927
-30.0 C (-22.0 F)
1928
-28.3 C (-18.9 F)
1929
-29.4 C (-20.9 F)
1930
-28.9 C (-20.0 F)
1931
-29.4 C (-20.9 F)
1932
-28.3 C (-18.9 F)
1933
-36.7 C (-34.1 F)
1934
-33.3 C (-27.9 F)
1935
-30.6 C (-23.1 F)
Wettest day (Rx1day)
The wettest day of the year at Ottawa, 1872 to 1935. The record is 94.0 mm (3.7 in) in 1887, marked on the chart; the median year is 39.9 mm (1.6 in).
Wettest day (Rx1day) at Ottawa by year
Year
Wettest day (Rx1day)
1872
33.0 mm (1.3 in)
1873
36.8 mm (1.4 in)
1874
25.4 mm (1.0 in)
1875
38.1 mm (1.5 in)
1876
50.8 mm (2.0 in)
1877
30.5 mm (1.2 in)
1878
38.6 mm (1.5 in)
1879
38.1 mm (1.5 in)
1880
40.9 mm (1.6 in)
1881
71.1 mm (2.8 in)
1882
15.2 mm (0.6 in)
1883
40.1 mm (1.6 in)
1884
36.1 mm (1.4 in)
1885
50.8 mm (2.0 in)
1886
54.1 mm (2.1 in)
1887
94.0 mm (3.7 in)
1888
36.3 mm (1.4 in)
1889
25.1 mm (1.0 in)
1890
n/a
1899
41.1 mm (1.6 in)
1900
57.4 mm (2.3 in)
1901
39.1 mm (1.5 in)
1902
43.2 mm (1.7 in)
1903
41.9 mm (1.6 in)
1904
44.7 mm (1.8 in)
1905
53.1 mm (2.1 in)
1906
41.1 mm (1.6 in)
1907
47.8 mm (1.9 in)
1908
39.6 mm (1.6 in)
1909
37.6 mm (1.5 in)
1910
39.9 mm (1.6 in)
1911
36.3 mm (1.4 in)
1912
54.1 mm (2.1 in)
1913
54.1 mm (2.1 in)
1914
22.9 mm (0.9 in)
1915
43.7 mm (1.7 in)
1916
53.3 mm (2.1 in)
1917
34.8 mm (1.4 in)
1918
61.7 mm (2.4 in)
1919
46.0 mm (1.8 in)
1920
38.9 mm (1.5 in)
1921
51.6 mm (2.0 in)
1922
30.5 mm (1.2 in)
1923
42.9 mm (1.7 in)
1924
26.7 mm (1.1 in)
1925
38.9 mm (1.5 in)
1926
50.0 mm (2.0 in)
1927
43.4 mm (1.7 in)
1928
53.8 mm (2.1 in)
1929
31.0 mm (1.2 in)
1930
34.0 mm (1.3 in)
1931
27.2 mm (1.1 in)
1932
39.4 mm (1.6 in)
1933
41.4 mm (1.6 in)
1934
39.9 mm (1.6 in)
1935
14.2 mm (0.6 in)
Wettest five days (Rx5day)
The wettest five days of the year at Ottawa, 1872 to 1935. The record is 158.8 mm (6.3 in) in 1885, marked on the chart; the median year is 63.8 mm (2.5 in).
Wettest five days (Rx5day) at Ottawa by year
Year
Wettest five days (Rx5day)
1872
43.0 mm (1.7 in)
1873
59.2 mm (2.3 in)
1874
59.7 mm (2.4 in)
1875
61.0 mm (2.4 in)
1876
72.9 mm (2.9 in)
1877
58.4 mm (2.3 in)
1878
63.3 mm (2.5 in)
1879
44.2 mm (1.7 in)
1880
44.7 mm (1.8 in)
1881
82.3 mm (3.2 in)
1882
33.0 mm (1.3 in)
1883
45.4 mm (1.8 in)
1884
57.1 mm (2.2 in)
1885
158.8 mm (6.3 in)
1886
119.4 mm (4.7 in)
1887
107.7 mm (4.2 in)
1888
76.9 mm (3.0 in)
1889
65.8 mm (2.6 in)
1890
n/a
1899
87.9 mm (3.5 in)
1900
78.8 mm (3.1 in)
1901
56.1 mm (2.2 in)
1902
57.2 mm (2.3 in)
1903
75.7 mm (3.0 in)
1904
55.0 mm (2.2 in)
1905
69.4 mm (2.7 in)
1906
75.9 mm (3.0 in)
1907
76.5 mm (3.0 in)
1908
55.9 mm (2.2 in)
1909
58.2 mm (2.3 in)
1910
61.5 mm (2.4 in)
1911
38.3 mm (1.5 in)
1912
67.7 mm (2.7 in)
1913
71.6 mm (2.8 in)
1914
58.9 mm (2.3 in)
1915
77.3 mm (3.0 in)
1916
94.2 mm (3.7 in)
1917
57.9 mm (2.3 in)
1918
75.7 mm (3.0 in)
1919
63.8 mm (2.5 in)
1920
59.0 mm (2.3 in)
1921
85.6 mm (3.4 in)
1922
44.5 mm (1.8 in)
1923
73.9 mm (2.9 in)
1924
59.0 mm (2.3 in)
1925
77.5 mm (3.1 in)
1926
80.0 mm (3.1 in)
1927
74.5 mm (2.9 in)
1928
84.0 mm (3.3 in)
1929
49.8 mm (2.0 in)
1930
66.2 mm (2.6 in)
1931
36.3 mm (1.4 in)
1932
78.5 mm (3.1 in)
1933
58.7 mm (2.3 in)
1934
73.7 mm (2.9 in)
1935
29.2 mm (1.1 in)
Longest dry spell (CDD)
The longest dry spell of the year at Ottawa, 1872 to 1935. The record is 36 days in 1881, marked on the chart; the median year is 15 days.
Longest dry spell (CDD) at Ottawa by year
Year
Longest dry spell (CDD)
1872
14 days
1873
23 days
1874
12 days
1875
19 days
1876
17 days
1877
13 days
1878
7 days
1879
27 days
1880
12 days
1881
36 days
1882
7 days
1883
15 days
1884
15 days
1885
17 days
1886
12 days
1887
18 days
1888
22 days
1889
24 days
1890
n/a
1899
17 days
1900
18 days
1901
15 days
1902
15 days
1903
23 days
1904
16 days
1905
14 days
1906
17 days
1907
11 days
1908
13 days
1909
14 days
1910
12 days
1911
17 days
1912
18 days
1913
18 days
1914
16 days
1915
22 days
1916
13 days
1917
18 days
1918
12 days
1919
15 days
1920
11 days
1921
14 days
1922
18 days
1923
14 days
1924
20 days
1925
14 days
1926
10 days
1927
15 days
1928
15 days
1929
13 days
1930
17 days
1931
14 days
1932
19 days
1933
12 days
1934
19 days
1935
11 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
47 years with a frost
Across 47 years with a frost, the median last spring frost at Ottawa falls on 4 May and the median first autumn frost on 7 October, which leaves a median of 153 days between them.
Fitted over all years, the growing season changes by +2.0 days per decade at this station.
Frost dates and growing season at Ottawa
Measure
Median, all years
Earliest period
Recent period (1905 to 1934)
Recent against earliest
Fitted trend
Last spring frost
4 May
n/a
4 May
n/a
-0.1 days per decade
First autumn frost
7 October
n/a
8 October
n/a
+2.0 days per decade
Growing days
153 days
n/a
155 days
n/a
+2.0 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
45 years, 1873 to 1934
A day with at least 41.6 mm (1.6 in) of rain is expected about once in 2 years. A day with at least 76.6 mm (3.0 in) of rain is expected about once in 100 years.
Rainfall return levels at Ottawa: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
41.6 mm (1.6 in)
5 years
51.5 mm (2.0 in)
10 years
57.9 mm (2.3 in)
25 years
65.6 mm (2.6 in)
50 years
71.2 mm (2.8 in)
Longer than the 45 years of record
100 years
76.6 mm (3.0 in)
Longer than the 45 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, 45 years of values from 1873 to 1934.
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: 94.0 mm (3.7 in) in 1887; 61.7 mm (2.4 in) in 1918; 57.4 mm (2.3 in) in 1900.
Station Changes
1 suspected
One change was suspected in the annual mean temperature of Ottawa, at 1900. Each is measured against neighbouring stations.
Relative to 5 neighbouring stations, the station's annual mean temperature from 1900 ran 0.8 C (1.4 F) higher than in the years before (likely change).
Suspected changes in the annual mean temperature at Ottawa, against neighbouring stations
Year
Shift (C)
Shift (F)
Strength
Neighbours
1900
+0.8
+1.4
likely
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 Ottawa standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Ottawa 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.