Alton Threshold Days by Year (USC00130181)
20 fixed thresholds counted per year at Alton (USC00130181): hot days, frost, tropical nights and heavy rain, with the most days in a year.
Key Facts for Alton Thresholds
- Alton: days with 10 mm (0.39 in) or more of precipitation in 94 years, most in 1984 with 30.
- Alton: days with 25 mm (0.98 in) or more of precipitation in 93 years, most in 1944 with 10.
- Alton: days with 10 cm (3.9 in) or more of snowfall in 61 years, most in 1993 with 6.
- Alton: days with 50 mm (1.97 in) or more of precipitation in 52 years, most in 1942 with 3.
- 20 fixed thresholds have at least one qualifying day at Alton.
Days at or above 30 C (86 F)
46 years with a qualifying day| Year | Days | Decade average |
|---|---|---|
| 1906 | 25 | 36 |
| 1907 | 26 | 36 |
| 1908 | 41 | 36 |
| 1909 | 52 | 36 |
| 1910 | 49 | 45.3 |
| 1912 | 41 | 45.3 |
| 1913 | 58 | 45.3 |
| 1914 | 55 | 45.3 |
| 1915 | 13 | 45.3 |
| 1916 | 56 | 45.3 |
| 1917 | 33 | 45.3 |
| 1918 | 49 | 45.3 |
| 1919 | 54 | 45.3 |
| 1920 | 36 | 43.3 |
| 1921 | 70 | 43.3 |
| 1922 | 53 | 43.3 |
| 1923 | 39 | 43.3 |
| 1924 | 26 | 43.3 |
| 1925 | 60 | 43.3 |
| 1926 | 46 | 43.3 |
| 1927 | 36 | 43.3 |
| 1928 | 31 | 43.3 |
| 1929 | 36 | 43.3 |
| 1930 | 51 | 63.2 |
| 1931 | 76 | 63.2 |
| 1932 | 46 | 63.2 |
| 1933 | 69 | 63.2 |
| 1934 | 71 | 63.2 |
| 1935 | 57 | 63.2 |
| 1936 | 80 | 63.2 |
| 1937 | 60 | 63.2 |
| 1938 | 62 | 63.2 |
| 1939 | 60 | 63.2 |
| 1940 | 42 | 44.2 |
| 1941 | 54 | 44.2 |
| 1942 | 32 | 44.2 |
| 1943 | 44 | 44.2 |
| 1944 | 25 | 44.2 |
| 1945 | 31 | 44.2 |
| 1946 | 47 | 44.2 |
| 1947 | 60 | 44.2 |
| 1948 | 50 | 44.2 |
| 1949 | 57 | 44.2 |
| 1950 | 34 | 49 |
| 1951 | 36 | 49 |
| 1952 | 77 | 49 |
| Year | First date | Last date |
|---|---|---|
| 1906 | 1906-04-24 | 1906-09-10 |
| 1907 | 1907-05-12 | 1907-09-19 |
| 1908 | 1908-05-19 | 1908-09-22 |
| 1909 | 1909-05-05 | 1909-08-28 |
| 1910 | 1910-03-23 | 1910-10-16 |
| 1912 | 1912-05-19 | 1912-10-05 |
| 1913 | 1913-04-30 | 1913-09-07 |
| 1914 | 1914-04-17 | 1914-09-05 |
| 1915 | 1915-05-10 | 1915-08-15 |
| 1916 | 1916-05-05 | 1916-09-05 |
| 1917 | 1917-05-17 | 1917-08-26 |
| 1918 | 1918-05-03 | 1918-08-27 |
| 1919 | 1919-05-28 | 1919-09-20 |
| 1920 | 1920-06-07 | 1920-09-25 |
| 1921 | 1921-04-24 | 1921-09-23 |
| 1922 | 1922-06-04 | 1922-10-04 |
| 1923 | 1923-06-01 | 1923-08-19 |
| 1924 | 1924-05-05 | 1924-08-30 |
| 1925 | 1925-05-20 | 1925-09-19 |
| 1926 | 1926-04-29 | 1926-09-17 |
| 1927 | 1927-04-26 | 1927-09-17 |
| 1928 | 1928-05-09 | 1928-10-10 |
| 1929 | 1929-06-15 | 1929-09-03 |
| 1930 | 1930-05-21 | 1930-10-10 |
| 1931 | 1931-04-07 | 1931-09-20 |
| 1932 | 1932-05-13 | 1932-10-02 |
| 1933 | 1933-05-16 | 1933-09-25 |
| 1934 | 1934-04-30 | 1934-10-12 |
| 1935 | 1935-06-12 | 1935-09-24 |
| 1936 | 1936-05-05 | 1936-09-22 |
| 1937 | 1937-05-29 | 1937-10-29 |
| 1938 | 1938-06-05 | 1938-10-07 |
| 1939 | 1939-05-04 | 1939-09-22 |
| 1940 | 1940-05-12 | 1940-09-22 |
| 1941 | 1941-05-14 | 1941-09-20 |
| 1942 | 1942-04-29 | 1942-09-11 |
| 1943 | 1943-03-30 | 1943-09-05 |
| 1944 | 1944-05-14 | 1944-09-17 |
| 1945 | 1945-06-22 | 1945-10-18 |
| 1946 | 1946-06-06 | 1946-09-05 |
| 1947 | 1947-06-09 | 1947-10-21 |
| 1948 | 1948-04-18 | 1948-09-19 |
| 1949 | 1949-04-25 | 1949-09-20 |
| 1950 | 1950-05-23 | 1950-10-30 |
| 1951 | 1951-06-16 | 1951-10-02 |
| 1952 | 1952-04-27 | 1952-09-30 |
Every Fixed Threshold
| Threshold | Years with a qualifying day | Most days in a year | Year | Latest year days |
|---|---|---|---|---|
| 30 C (86 F): Days | 46 | 80 | 1936 | 77 |
| 35 C (95 F): Days | 40 | 41 | 1936 | 13 |
| 40 C (104 F): Days | 8 | 9 | 1936 | 1 |
| 90 F (32.2 C): Days | 46 | 63 | 1936 | 47 |
| 100 F (37.8 C): Days | 23 | 23 | 1936 | 2 |
| 110 F (43.3 C): Days | 1 | 2 | 1936 | 2 |
| 0 C (32 F): Ice days (max | 46 | 80 | 1929 | 55 |
| 0 C (32 F): Frost days (min | 46 | 183 | 1907 | 166 |
| -10 C (14 F): Days with min | 46 | 84 | 1917 | 50 |
| -20 C (-4 F): Days with min | 46 | 42 | 1916 | 10 |
| -30 C (-22 F): Days with min | 21 | 10 | 1936 | 1 |
| -40 C (-40 F): Days with min | 1 | 1 | 1912 | 1 |
| 20 C (68 F): Tropical nights (min | 46 | 37 | 1931 | 19 |
| 25 C (77 F): Days with min | 13 | 4 | 1936 | 1 |
| 10 mm (0.39 in): Days with 10 mm or more rain | 94 | 30 | 1984 | 19 |
| 25 mm (0.98 in): Days with 25 mm or more rain | 93 | 10 | 1944 | 2 |
| 50 mm (1.97 in): Days with 50 mm or more rain | 52 | 3 | 1942 | 1 |
| 100 mm (3.94 in): Days with 100 mm or more rain | 3 | 1 | 1970 | 1 |
| 10 cm (3.9 in): Days with 10 cm or more snowfall | 61 | 6 | 1993 | 2 |
| 25 cm (9.8 in): Days with 25 cm or more snowfall | 4 | 1 | 1940 | 1 |
Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1906.
Download the Data
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). Threshold counts are computed by this site.
Data as of . Last revised (2025-12-31).