Record highRecord low2026 daily maximum2026 daily minimum
The band shows the record high and record low for each calendar day at Alton. 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 Alton, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
15.0 C (59.0 F)
-33.9 C (-29.0 F)
n/a
n/a
Feb
17.2 C (63.0 F)
-35.6 C (-32.1 F)
n/a
n/a
Mar
27.2 C (81.0 F)
-30.6 C (-23.1 F)
n/a
n/a
Apr
28.9 C (84.0 F)
-20.6 C (-5.1 F)
n/a
n/a
May
32.8 C (91.0 F)
-7.8 C (18.0 F)
n/a
n/a
Jun
36.1 C (97.0 F)
-6.7 C (19.9 F)
n/a
n/a
Jul
38.3 C (100.9 F)
1.1 C (34.0 F)
n/a
n/a
Aug
37.2 C (99.0 F)
-1.7 C (28.9 F)
n/a
n/a
Sep
36.1 C (97.0 F)
-6.1 C (21.0 F)
n/a
n/a
Oct
32.2 C (90.0 F)
-13.3 C (8.1 F)
n/a
n/a
Nov
23.3 C (73.9 F)
-22.2 C (-8.0 F)
n/a
n/a
Dec
13.3 C (55.9 F)
-31.7 C (-25.1 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Alton still stand. 1904 holds the most, with 52.
Standing records at Alton by the year they were set
Year set
Standing records
1887
26
1888
36
1889
24
1890
27
1891
25
1892
19
1893
12
1894
25
1895
51
1896
34
1897
19
1898
23
1899
31
1900
42
1901
15
1902
22
1903
30
1904
52
1905
18
1906
26
1907
25
1908
25
1909
24
1910
34
1911
34
1912
36
1913
34
1914
31
1915
17
1916
32
1917
17
1918
27
1919
18
1920
24
1921
29
1922
13
1923
25
1924
23
1925
29
1926
13
1927
23
1928
11
1929
23
1930
31
1931
28
1932
12
1933
37
1934
21
1935
16
1947
15
1948
21
1949
36
1950
19
1951
13
1952
15
1953
12
1954
10
1955
5
1959
4
1961
7
1962
18
1963
18
1964
2
All-Time Record Progression
3 new records
3 all-time records were set at Alton between 29 January 1930 and 26 August 1949. Each dot is a new record.
When Alton set new all-time records
Date
Kind
Detail
1930-01-29
Record daily snowfall
Record daily snowfall 71.1 cm (28.0 in)
1934-02-09
Record low maximum temperature
Record low maximum temperature -26.7 C (-16.1 F)
1949-08-26
Record high minimum temperature
Record high minimum temperature 24.4 C (75.9 F)
Wettest Day of Each Month
Sep: 104.4 mm (4.1 in)
The wettest day on record for each calendar month at Alton. The most was 104.4 mm (4.1 in) on 24 September 1904.
Record daily precipitation for each month at Alton
Month
Record daily precipitation (mm)
Date
Jan
71.1 mm (2.8 in)
29 January 1930
Feb
55.9 mm (2.2 in)
15 February 1954
Mar
35.6 mm (1.4 in)
7 March 1931
Apr
48.8 mm (1.9 in)
23 April 1921
May
72.9 mm (2.9 in)
22 May 1912
Jun
70.1 mm (2.8 in)
5 June 1890
Jul
63.5 mm (2.5 in)
19 July 1921
Aug
87.6 mm (3.4 in)
9 August 1891
Sep
104.4 mm (4.1 in)
24 September 1904
Oct
57.2 mm (2.3 in)
12 October 1949
Nov
76.5 mm (3.0 in)
5 November 1935
Dec
52.1 mm (2.1 in)
16 December 1893
Period of Record Coverage
1887 to 1964
Complete yearUnder 90 percent of days
63 years of record at Alton, 1887 to 1964. 8 years have data for under 90 percent of days and are left out of rankings: 1935, 1949, 1950, 1954, 1955, 1959, 1961, 1964.
Cooler than the station meanWarmer than the station mean
One stripe for each of 49 complete years at Alton, 1887 to 1962. Blue stripes are years cooler than the station's own mean of 5.3 C (41.5 F); red stripes are warmer. The coolest year was 1904, at 3.0 C (37.5 F), and the warmest was 1921, at 7.4 C (45.3 F). The strongest colour marks a difference of 2.3 C (4.1 F).
Annual mean temperature at Alton as warming stripes, 1887 to 1962
Year
Annual mean temperature
Difference from the station mean
1887
4.9 C
-0.40 C
1888
3.7 C
-1.61 C
1889
5.3 C
-0.02 C
1890
4.9 C
-0.36 C
1891
5.5 C
+0.22 C
1892
4.5 C
-0.81 C
1893
4.2 C
-1.13 C
1894
5.9 C
+0.59 C
1895
4.4 C
-0.92 C
1896
5.2 C
-0.12 C
1897
5.4 C
+0.13 C
1898
6.3 C
+1.00 C
1899
5.3 C
-0.01 C
1900
6.5 C
+1.18 C
1901
5.1 C
-0.23 C
1902
5.2 C
-0.12 C
1903
5.1 C
-0.24 C
1904
3.0 C
-2.26 C
1905
4.5 C
-0.79 C
1906
5.2 C
-0.13 C
1907
4.0 C
-1.30 C
1908
5.2 C
-0.10 C
1909
4.7 C
-0.59 C
1910
4.5 C
-0.81 C
1911
5.3 C
+0.03 C
1912
3.6 C
-1.75 C
1913
5.9 C
+0.60 C
1914
5.7 C
+0.35 C
1915
5.6 C
+0.32 C
1916
5.5 C
+0.23 C
1917
3.5 C
-1.82 C
1918
5.3 C
-0.05 C
1919
6.2 C
+0.93 C
1920
5.2 C
-0.06 C
1921
7.4 C
+2.11 C
1922
6.7 C
+1.36 C
1923
5.6 C
+0.25 C
1924
5.3 C
-0.03 C
1925
5.9 C
+0.62 C
1927
5.8 C
+0.47 C
1928
5.8 C
+0.45 C
1929
5.4 C
+0.05 C
1930
6.5 C
+1.22 C
1931
7.0 C
+1.73 C
1932
6.3 C
+1.00 C
1933
6.5 C
+1.18 C
1934
5.2 C
-0.07 C
1951
5.0 C
-0.28 C
1962
5.4 C
+0.07 C
The annual mean temperature here has risen by 0.20 C (0.05 to 0.34) per decade over 1887 to 1962. In Fahrenheit: 0.4 F (0.1 to 0.6) per decade. The slope is a straight line fitted to 49 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Alton
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.20 C (0.05 to 0.34) per decade
0.4 F (0.1 to 0.6) per decade
1887 to 1962
49
Rise
Mean daily maximum
0.16 C (0.00 to 0.32) per decade
0.29 F (-0.01 to 0.58) per decade
1887 to 1962
49
Not clearly different from zero
Mean daily minimum
0.23 C (0.05 to 0.42) per decade
0.4 F (0.1 to 0.7) per decade
1887 to 1962
49
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
1887 to 1964
Yearly extremes at Alton: 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)
1911
33.3 C (91.9 F)
63
Coldest night (TNn)
-35.6 C (-32.1 F)
1908
-28.3 C (-18.9 F)
63
Wettest day (Rx1day)
104.4 mm (4.1 in)
1904
49.8 mm (2.0 in)
62
Wettest five days (Rx5day)
114.4 mm (4.5 in)
1889
68.9 mm (2.7 in)
62
Longest dry spell (CDD)
39 days
1908
17 days
62
Hottest day (TXx)
The hottest day of the year at Alton, 1887 to 1964. The record is 38.3 C (100.9 F) in 1911, marked on the chart; the median year is 33.3 C (91.9 F).
Hottest day (TXx) at Alton by year
Year
Hottest day (TXx)
1887
33.9 C (93.0 F)
1888
33.3 C (91.9 F)
1889
32.2 C (90.0 F)
1890
33.3 C (91.9 F)
1891
31.7 C (89.1 F)
1892
32.2 C (90.0 F)
1893
33.3 C (91.9 F)
1894
33.9 C (93.0 F)
1895
32.8 C (91.0 F)
1896
33.3 C (91.9 F)
1897
34.4 C (93.9 F)
1898
35.0 C (95.0 F)
1899
35.0 C (95.0 F)
1900
35.6 C (96.1 F)
1901
34.4 C (93.9 F)
1902
31.1 C (88.0 F)
1903
32.2 C (90.0 F)
1904
32.2 C (90.0 F)
1905
32.2 C (90.0 F)
1906
31.1 C (88.0 F)
1907
32.8 C (91.0 F)
1908
33.3 C (91.9 F)
1909
32.2 C (90.0 F)
1910
33.3 C (91.9 F)
1911
38.3 C (100.9 F)
1912
32.8 C (91.0 F)
1913
35.0 C (95.0 F)
1914
35.6 C (96.1 F)
1915
29.4 C (84.9 F)
1916
36.7 C (98.1 F)
1917
34.4 C (93.9 F)
1918
37.2 C (99.0 F)
1919
34.4 C (93.9 F)
1920
32.2 C (90.0 F)
1921
35.0 C (95.0 F)
1922
33.3 C (91.9 F)
1923
32.8 C (91.0 F)
1924
32.2 C (90.0 F)
1925
35.0 C (95.0 F)
1926
32.8 C (91.0 F)
1927
33.9 C (93.0 F)
1928
31.1 C (88.0 F)
1929
33.3 C (91.9 F)
1930
33.9 C (93.0 F)
1931
36.7 C (98.1 F)
1932
33.9 C (93.0 F)
1933
35.6 C (96.1 F)
1934
36.1 C (97.0 F)
1935
33.3 C (91.9 F)
1947
30.0 C (86.0 F)
1948
33.9 C (93.0 F)
1949
33.9 C (93.0 F)
1950
28.9 C (84.0 F)
1951
31.1 C (88.0 F)
1952
33.3 C (91.9 F)
1953
35.0 C (95.0 F)
1954
30.6 C (87.1 F)
1955
32.8 C (91.0 F)
1959
18.3 C (64.9 F)
1961
30.6 C (87.1 F)
1962
31.1 C (88.0 F)
1963
32.8 C (91.0 F)
1964
6.1 C (43.0 F)
Coldest night (TNn)
The coldest night of the year at Alton, 1887 to 1964. The record is -35.6 C (-32.1 F) in 1908, marked on the chart; the median year is -28.3 C (-18.9 F).
Coldest night (TNn) at Alton by year
Year
Coldest night (TNn)
1887
-24.4 C (-11.9 F)
1888
-30.6 C (-23.1 F)
1889
-27.2 C (-17.0 F)
1890
-23.9 C (-11.0 F)
1891
-22.2 C (-8.0 F)
1892
-25.6 C (-14.1 F)
1893
-26.7 C (-16.1 F)
1894
-30.0 C (-22.0 F)
1895
-32.8 C (-27.0 F)
1896
-33.9 C (-29.0 F)
1897
-28.3 C (-18.9 F)
1898
-30.0 C (-22.0 F)
1899
-29.4 C (-20.9 F)
1900
-28.9 C (-20.0 F)
1901
-29.4 C (-20.9 F)
1902
-22.2 C (-8.0 F)
1903
-28.9 C (-20.0 F)
1904
-33.9 C (-29.0 F)
1905
-29.4 C (-20.9 F)
1906
-30.6 C (-23.1 F)
1907
-29.4 C (-20.9 F)
1908
-35.6 C (-32.1 F)
1909
-28.3 C (-18.9 F)
1910
-33.3 C (-27.9 F)
1911
-25.0 C (-13.0 F)
1912
-35.6 C (-32.1 F)
1913
-26.1 C (-15.0 F)
1914
-32.8 C (-27.0 F)
1915
-23.3 C (-9.9 F)
1916
-31.1 C (-24.0 F)
1917
-30.6 C (-23.1 F)
1918
-33.3 C (-27.9 F)
1919
-26.7 C (-16.1 F)
1920
-30.6 C (-23.1 F)
1921
-25.0 C (-13.0 F)
1922
-26.1 C (-15.0 F)
1923
-25.6 C (-14.1 F)
1924
-27.8 C (-18.0 F)
1925
-32.2 C (-26.0 F)
1926
-23.9 C (-11.0 F)
1927
-30.6 C (-23.1 F)
1928
-26.1 C (-15.0 F)
1929
-26.1 C (-15.0 F)
1930
-27.2 C (-17.0 F)
1931
-26.1 C (-15.0 F)
1932
-22.2 C (-8.0 F)
1933
-31.7 C (-25.1 F)
1934
-33.9 C (-29.0 F)
1935
-30.0 C (-22.0 F)
1947
-17.2 C (1.0 F)
1948
-31.7 C (-25.1 F)
1949
-20.6 C (-5.1 F)
1950
-26.1 C (-15.0 F)
1951
-26.7 C (-16.1 F)
1952
-28.9 C (-20.0 F)
1953
-20.6 C (-5.1 F)
1954
-26.7 C (-16.1 F)
1955
-23.3 C (-9.9 F)
1959
-19.4 C (-2.9 F)
1961
-20.0 C (-4.0 F)
1962
-30.6 C (-23.1 F)
1963
-28.9 C (-20.0 F)
1964
-25.0 C (-13.0 F)
Wettest day (Rx1day)
The wettest day of the year at Alton, 1887 to 1964. The record is 104.4 mm (4.1 in) in 1904, marked on the chart; the median year is 49.8 mm (2.0 in).
Wettest day (Rx1day) at Alton by year
Year
Wettest day (Rx1day)
1887
48.5 mm (1.9 in)
1888
58.9 mm (2.3 in)
1889
71.4 mm (2.8 in)
1890
70.1 mm (2.8 in)
1891
87.6 mm (3.4 in)
1892
53.6 mm (2.1 in)
1893
52.6 mm (2.1 in)
1894
36.3 mm (1.4 in)
1895
51.6 mm (2.0 in)
1896
40.1 mm (1.6 in)
1897
47.2 mm (1.9 in)
1898
42.2 mm (1.7 in)
1899
70.6 mm (2.8 in)
1900
46.7 mm (1.8 in)
1901
61.7 mm (2.4 in)
1902
39.9 mm (1.6 in)
1903
36.1 mm (1.4 in)
1904
104.4 mm (4.1 in)
1905
64.8 mm (2.6 in)
1906
48.3 mm (1.9 in)
1907
38.9 mm (1.5 in)
1908
58.7 mm (2.3 in)
1909
60.5 mm (2.4 in)
1910
35.6 mm (1.4 in)
1911
50.8 mm (2.0 in)
1912
72.9 mm (2.9 in)
1913
40.9 mm (1.6 in)
1914
35.6 mm (1.4 in)
1915
71.6 mm (2.8 in)
1916
54.4 mm (2.1 in)
1917
41.1 mm (1.6 in)
1918
43.2 mm (1.7 in)
1919
33.5 mm (1.3 in)
1920
48.8 mm (1.9 in)
1921
63.5 mm (2.5 in)
1922
40.6 mm (1.6 in)
1923
52.1 mm (2.1 in)
1924
33.0 mm (1.3 in)
1925
22.4 mm (0.9 in)
1926
50.8 mm (2.0 in)
1927
40.6 mm (1.6 in)
1928
53.8 mm (2.1 in)
1929
47.5 mm (1.9 in)
1930
71.1 mm (2.8 in)
1931
38.4 mm (1.5 in)
1932
58.4 mm (2.3 in)
1933
28.4 mm (1.1 in)
1934
38.1 mm (1.5 in)
1935
76.5 mm (3.0 in)
1947
47.0 mm (1.9 in)
1948
35.6 mm (1.4 in)
1949
57.2 mm (2.3 in)
1950
35.6 mm (1.4 in)
1951
43.2 mm (1.7 in)
1952
36.8 mm (1.4 in)
1953
50.8 mm (2.0 in)
1954
55.9 mm (2.2 in)
1955
50.8 mm (2.0 in)
1959
32.0 mm (1.3 in)
1961
52.1 mm (2.1 in)
1962
54.6 mm (2.1 in)
1963
50.8 mm (2.0 in)
1964
n/a
Wettest five days (Rx5day)
The wettest five days of the year at Alton, 1887 to 1964. The record is 114.4 mm (4.5 in) in 1889, marked on the chart; the median year is 68.9 mm (2.7 in).
Wettest five days (Rx5day) at Alton by year
Year
Wettest five days (Rx5day)
1887
64.8 mm (2.6 in)
1888
89.6 mm (3.5 in)
1889
114.4 mm (4.5 in)
1890
87.1 mm (3.4 in)
1891
88.6 mm (3.5 in)
1892
63.5 mm (2.5 in)
1893
69.9 mm (2.8 in)
1894
81.0 mm (3.2 in)
1895
54.1 mm (2.1 in)
1896
59.7 mm (2.4 in)
1897
76.1 mm (3.0 in)
1898
56.9 mm (2.2 in)
1899
78.7 mm (3.1 in)
1900
66.3 mm (2.6 in)
1901
98.5 mm (3.9 in)
1902
75.5 mm (3.0 in)
1903
72.7 mm (2.9 in)
1904
106.9 mm (4.2 in)
1905
76.7 mm (3.0 in)
1906
100.6 mm (4.0 in)
1907
43.2 mm (1.7 in)
1908
72.0 mm (2.8 in)
1909
66.3 mm (2.6 in)
1910
53.1 mm (2.1 in)
1911
74.4 mm (2.9 in)
1912
74.2 mm (2.9 in)
1913
67.4 mm (2.7 in)
1914
48.8 mm (1.9 in)
1915
100.9 mm (4.0 in)
1916
59.5 mm (2.3 in)
1917
68.7 mm (2.7 in)
1918
64.3 mm (2.5 in)
1919
43.9 mm (1.7 in)
1920
64.5 mm (2.5 in)
1921
63.5 mm (2.5 in)
1922
48.3 mm (1.9 in)
1923
52.9 mm (2.1 in)
1924
41.4 mm (1.6 in)
1925
48.1 mm (1.9 in)
1926
113.0 mm (4.4 in)
1927
66.5 mm (2.6 in)
1928
75.4 mm (3.0 in)
1929
82.8 mm (3.3 in)
1930
106.7 mm (4.2 in)
1931
74.2 mm (2.9 in)
1932
59.9 mm (2.4 in)
1933
59.6 mm (2.3 in)
1934
60.3 mm (2.4 in)
1935
106.8 mm (4.2 in)
1947
70.6 mm (2.8 in)
1948
69.1 mm (2.7 in)
1949
74.0 mm (2.9 in)
1950
82.6 mm (3.3 in)
1951
65.9 mm (2.6 in)
1952
65.8 mm (2.6 in)
1953
63.5 mm (2.5 in)
1954
81.3 mm (3.2 in)
1955
55.6 mm (2.2 in)
1959
52.3 mm (2.1 in)
1961
65.3 mm (2.6 in)
1962
82.5 mm (3.2 in)
1963
76.2 mm (3.0 in)
1964
n/a
Longest dry spell (CDD)
The longest dry spell of the year at Alton, 1887 to 1964. The record is 39 days in 1908, marked on the chart; the median year is 17 days.
Longest dry spell (CDD) at Alton by year
Year
Longest dry spell (CDD)
1887
17 days
1888
13 days
1889
21 days
1890
14 days
1891
21 days
1892
14 days
1893
13 days
1894
14 days
1895
13 days
1896
12 days
1897
15 days
1898
17 days
1899
20 days
1900
17 days
1901
17 days
1902
18 days
1903
15 days
1904
13 days
1905
12 days
1906
12 days
1907
14 days
1908
39 days
1909
12 days
1910
15 days
1911
15 days
1912
19 days
1913
13 days
1914
16 days
1915
18 days
1916
24 days
1917
15 days
1918
17 days
1919
12 days
1920
16 days
1921
12 days
1922
17 days
1923
21 days
1924
36 days
1925
15 days
1926
19 days
1927
20 days
1928
15 days
1929
20 days
1930
12 days
1931
11 days
1932
16 days
1933
22 days
1934
18 days
1935
19 days
1947
36 days
1948
17 days
1949
32 days
1950
14 days
1951
22 days
1952
24 days
1953
17 days
1954
23 days
1955
17 days
1959
14 days
1961
16 days
1962
10 days
1963
31 days
1964
n/a
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
49 years with a frost
Across 49 years with a frost, the median last spring frost at Alton falls on 22 May and the median first autumn frost on 21 September, which leaves a median of 123 days between them.
Fitted over all years, the growing season changes by -0.5 days per decade at this station.
Frost dates and growing season at Alton
Measure
Median, all years
Earliest period
Recent period (1906 to 1962)
Recent against earliest
Fitted trend
Last spring frost
22 May
n/a
23 May
n/a
-0.6 days per decade
First autumn frost
21 September
n/a
23 September
n/a
-1.1 days per decade
Growing days
123 days
n/a
123 days
n/a
-0.5 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
49 years, 1887 to 1951
A day with at least 49.0 mm (1.9 in) of rain is expected about once in 2 years. A day with at least 105.8 mm (4.2 in) of rain is expected about once in 100 years.
Rainfall return levels at Alton: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
49.0 mm (1.9 in)
5 years
62.7 mm (2.5 in)
10 years
72.4 mm (2.9 in)
25 years
85.3 mm (3.4 in)
50 years
95.4 mm (3.8 in)
Longer than the 49 years of record
100 years
105.8 mm (4.2 in)
Longer than the 49 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, 49 years of values from 1887 to 1951.
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: 104.4 mm (4.1 in) in 1904; 87.6 mm (3.4 in) in 1891; 76.5 mm (3.0 in) in 1935.
Station Changes
No change in the annual mean temperature of this station was found against its neighbours.
Download the Data
Data for Alton standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Alton 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 2026-10-15 (15 October 2026). Records are computed by this site and are not official.