Alta Threshold Days by Year (USC00130173)

19 fixed thresholds counted per year at Alta (USC00130173): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Alta Thresholds

Alta: days with a maximum temperature at or above 30 C (86 F) in 64 years, most in 1936 with 81.
Alta: days with a maximum temperature at or below 0 C (32 F) in 64 years, most in 1917 with 88.
Alta: nights with a minimum temperature at or below 0 C (32 F) in 64 years, most in 1907 with 187.
Alta: nights with a minimum temperature at or below -10 C (14 F) in 64 years, most in 1893 with 91.
19 fixed thresholds have at least one qualifying day at Alta.

Days at or above 30 C (86 F)

64 years with a qualifying day

Days per year at Alta with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 81 in 1936.

Days at or above 30 C (86 F) per year at Alta
Year	Days	Decade average
1893	40	47.6
1894	74	47.6
1895	47	47.6
1896	36	47.6
1897	57	47.6
1898	42	47.6
1899	37	47.6
1900	46	28.4
1901	63	28.4
1902	12	28.4
1903	8	28.4
1904	15	28.4
1905	25	28.4
1906	26	28.4
1907	26	28.4
1908	30	28.4
1909	33	28.4
1910	42	38.5
1911	63	38.5
1912	38	38.5
1913	59	38.5
1914	38	38.5
1915	5	38.5
1916	48	38.5
1917	28	38.5
1918	35	38.5
1919	29	38.5
1920	27	39.6
1921	55	39.6
1922	28	39.6
1923	32	39.6
1924	16	39.6
1925	57	39.6
1926	47	39.6
1927	45	39.6
1928	39	39.6
1929	50	39.6
1930	57	66
1931	78	66
1932	45	66
1933	66	66
1934	73	66
1935	63	66
1936	81	66
1937	64	66
1938	59	66
1939	74	66
1940	49	46.9
1941	54	46.9
1942	42	46.9
1945	29	46.9
1946	36	46.9
1947	64	46.9
1948	54	46.9
1949	47	46.9
1950	17	36.1
1951	11	36.1
1952	41	36.1
1953	45	36.1
1954	34	36.1
1955	57	36.1
1956	63	36.1
1957	30	36.1
1958	27	36.1

For each year, a bar from the first to the last day at Alta meeting 30 C (86 F).

First to last qualifying date each year at Alta
Year	First date	Last date
1893	1893-05-21	1893-09-18
1894	1894-05-14	1894-09-28
1895	1895-05-06	1895-09-20
1896	1896-05-06	1896-08-15
1897	1897-06-10	1897-10-14
1898	1898-05-24	1898-09-29
1899	1899-06-12	1899-10-12
1900	1900-05-11	1900-09-09
1901	1901-04-29	1901-09-06
1902	1902-05-17	1902-08-02
1903	1903-06-30	1903-08-04
1904	1904-06-23	1904-09-28
1905	1905-06-03	1905-08-29
1906	1906-04-24	1906-09-11
1907	1907-05-13	1907-09-19
1908	1908-04-14	1908-09-23
1909	1909-05-06	1909-08-28
1910	1910-04-29	1910-10-17
1911	1911-05-09	1911-09-18
1912	1912-05-23	1912-09-10
1913	1913-05-29	1913-09-08
1914	1914-05-26	1914-09-06
1915	1915-05-13	1915-08-07
1916	1916-05-07	1916-09-07
1917	1917-05-18	1917-08-22
1918	1918-05-04	1918-08-28
1919	1919-06-17	1919-09-20
1920	1920-06-07	1920-09-25
1921	1921-04-24	1921-09-23
1922	1922-06-06	1922-09-07
1923	1923-06-01	1923-09-05
1924	1924-04-24	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	1929-04-04	1929-09-03
1930	1930-04-10	1930-10-10
1931	1931-04-08	1931-09-20
1932	1932-05-13	1932-09-18
1933	1933-05-18	1933-09-18
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	1937-09-22
1938	1938-06-05	1938-10-04
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	1942-09-16
1945	1945-06-22	1945-09-07
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	1951-07-05	1951-10-01
1952	1952-05-04	1952-09-30
1953	1953-05-25	1953-10-02
1954	1954-04-14	1954-09-26
1955	1955-05-06	1955-09-18
1956	1956-05-18	1956-10-12
1957	1957-06-04	1957-08-31
1958	1958-05-11	1958-10-15

Every Fixed Threshold

Fixed thresholds at Alta
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	64	81	1936	27
35 C (95 F): Days	50	39	1936	1
40 C (104 F): Days	11	11	1936	1
90 F (32.2 C): Days	62	64	1936	7
100 F (37.8 C): Days	19	23	1936	4
110 F (43.3 C): Days	1	1	1936	1
0 C (32 F): Ice days (max	64	88	1917	69
0 C (32 F): Frost days (min	64	187	1907	153
-10 C (14 F): Days with min	64	91	1893	59
-20 C (-4 F): Days with min	64	40	1936	17
-30 C (-22 F): Days with min	23	7	1912	2
20 C (68 F): Tropical nights (min	64	35	1955	11
25 C (77 F): Days with min	9	5	1936	2
10 mm (0.39 in): Days with 10 mm or more rain	61	42	1915	16
25 mm (0.98 in): Days with 25 mm or more rain	61	12	1902	2
50 mm (1.97 in): Days with 50 mm or more rain	43	5	1914	1
100 mm (3.94 in): Days with 100 mm or more rain	8	1	1898	1
10 cm (3.9 in): Days with 10 cm or more snowfall	46	6	1924	1
25 cm (9.8 in): Days with 25 cm or more snowfall	4	1	1924	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1893.

Download the Data

Data for Alta 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). Threshold counts are computed by this site.

Data as of 2025-12-31. Last revised 31 December 2025 (2025-12-31).

Alta Threshold Days by Year (USC00130173)

Key Facts for Alta Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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