Hetch Hetchy Threshold Days by Year

17 fixed thresholds counted per year at Hetch Hetchy (USC00043939): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Hetch Hetchy Thresholds

Hetch Hetchy: days with a maximum temperature at or above 30 C (86 F) in 105 years, most in 2024 with 88.
Hetch Hetchy: days with a maximum temperature at or above 90 F (32.2 C) in 105 years, most in 2024 with 59.
Hetch Hetchy: nights with a minimum temperature at or below 0 C (32 F) in 105 years, most in 1912 with 162.
Hetch Hetchy: days with 10 mm (0.39 in) or more of precipitation in 101 years, most in 1983 with 53.
17 fixed thresholds have at least one qualifying day at Hetch Hetchy.

Days at or above 30 C (86 F)

105 years with a qualifying day

Days per year at Hetch Hetchy with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 88 in 2024.

Days at or above 30 C (86 F) per year at Hetch Hetchy
Year	Days	Decade average
1911	72	70.2
1912	56	70.2
1913	76	70.2
1915	79	70.2
1916	58	70.2
1919	80	70.2
1920	65	59
1922	65	59
1923	52	59
1924	26	59
1925	45	59
1926	70	59
1927	71	59
1928	67	59
1929	70	59
1930	59	68.1
1931	68	68.1
1932	67	68.1
1933	70	68.1
1934	72	68.1
1935	65	68.1
1936	78	68.1
1937	66	68.1
1938	63	68.1
1939	73	68.1
1940	61	53.8
1941	34	53.8
1942	57	53.8
1943	58	53.8
1944	53	53.8
1945	67	53.8
1946	64	53.8
1947	52	53.8
1948	46	53.8
1949	46	53.8
1950	58	59.3
1951	67	59.3
1952	58	59.3
1953	60	59.3
1954	50	59.3
1955	62	59.3
1956	40	59.3
1957	54	59.3
1958	67	59.3
1959	77	59.3
1960	73	50.9
1961	64	50.9
1962	56	50.9
1963	46	50.9
1964	48	50.9
1965	25	50.9
1967	60	50.9
1968	52	50.9
1969	34	50.9
1970	52	48.3
1971	54	48.3
1972	42	48.3
1974	53	48.3
1976	31	48.3
1977	58	48.3
1980	40	47.9
1981	64	47.9
1982	23	47.9
1983	33	47.9
1984	59	47.9
1985	57	47.9
1986	47	47.9
1987	55	47.9
1988	63	47.9
1989	38	47.9
1990	42	40.2
1991	50	40.2
1992	40	40.2
1993	34	40.2
1994	67	40.2
1995	38	40.2
1996	61	40.2
1997	26	40.2
1998	29	40.2
1999	15	40.2
2000	63	64.5
2001	63	64.5
2002	65	64.5
2003	66	64.5
2004	66	64.5
2005	48	64.5
2006	77	64.5
2007	72	64.5
2008	70	64.5
2009	55	64.5
2010	37	53.4
2011	32	53.4
2014	63	53.4
2015	67	53.4
2016	57	53.4
2017	63	53.4
2018	68	53.4
2019	40	53.4
2020	71	68.1
2021	82	68.1
2022	78	68.1
2023	51	68.1
2024	88	68.1
2025	62	68.1
2026	45	68.1

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

First to last qualifying date each year at Hetch Hetchy
Year	First date	Last date
1911	1911-06-10	1911-10-16
1912	1912-05-13	1912-09-23
1913	1913-05-24	1913-10-25
1915	1915-05-28	1915-10-25
1916	1916-06-05	1916-09-29
1919	1919-05-14	1919-09-25
1920	1920-05-16	1920-09-28
1922	1922-06-16	1922-09-25
1923	1923-06-28	1923-09-16
1924	1924-06-02	1924-09-15
1925	1925-06-18	1925-09-23
1926	1926-05-31	1926-10-26
1927	1927-04-24	1927-10-20
1928	1928-05-25	1928-10-08
1929	1929-06-20	1929-10-05
1930	1930-06-06	1930-09-15
1931	1931-04-20	1931-09-13
1932	1932-06-20	1932-10-05
1933	1933-05-28	1933-10-06
1934	1934-05-11	1934-10-12
1935	1935-06-04	1935-09-22
1936	1936-05-24	1936-10-11
1937	1937-05-14	1937-09-28
1938	1938-05-14	1938-09-23
1939	1939-05-29	1939-09-22
1940	1940-05-10	1940-10-13
1941	1941-05-23	1941-09-07
1942	1942-05-21	1942-10-06
1943	1943-05-24	1943-10-05
1944	1944-06-29	1944-09-29
1945	1945-06-13	1945-10-03
1946	1946-04-25	1946-09-30
1947	1947-05-02	1947-10-05
1948	1948-06-29	1948-09-15
1949	1949-05-26	1949-09-24
1950	1950-05-30	1950-10-14
1951	1951-05-26	1951-10-10
1952	1952-07-03	1952-10-06
1953	1953-06-23	1953-10-08
1954	1954-05-19	1954-10-16
1955	1955-05-21	1955-10-16
1956	1956-05-17	1956-09-24
1957	1957-06-03	1957-09-24
1958	1958-06-16	1958-10-06
1959	1959-05-13	1959-10-25
1960	1960-06-01	1960-09-27
1961	1961-06-14	1961-10-17
1962	1962-06-19	1962-10-02
1963	1963-06-17	1963-10-03
1964	1964-06-23	1964-10-07
1965	1965-07-05	1965-10-09
1967	1967-05-18	1967-09-02
1968	1968-06-17	1968-09-28
1969	1969-07-12	1969-09-11
1970	1970-05-17	1970-10-03
1971	1971-06-17	1971-10-14
1972	1972-05-14	1972-08-28
1974	1974-05-26	1974-09-25
1976	1976-05-13	1976-09-10
1977	1977-06-01	1977-09-11
1980	1980-06-29	1980-10-09
1981	1981-04-30	1981-09-19
1982	1982-05-25	1982-09-10
1983	1983-05-24	1983-09-20
1984	1984-05-28	1984-09-18
1985	1985-06-07	1985-10-06
1986	1986-05-26	1986-09-07
1987	1987-06-03	1987-10-08
1988	1988-06-15	1988-10-02
1989	1989-04-08	1989-09-15
1990	1990-06-21	1990-09-12
1991	1991-06-11	1991-10-16
1992	1992-06-01	1992-09-30
1993	1993-06-20	1993-10-04
1994	1994-06-10	1994-09-25
1995	1995-06-24	1995-09-21
1996	1996-06-03	1996-10-10
1997	1997-06-18	1997-10-01
1998	1998-07-15	1998-09-03
1999	1999-07-01	1999-09-30
2000	2000-05-22	2000-10-04
2001	2001-05-09	2001-10-04
2002	2002-05-31	2002-09-26
2003	2003-05-28	2003-09-29
2004	2004-05-04	2004-09-26
2005	2005-07-01	2005-09-03
2006	2006-05-15	2006-09-29
2007	2007-04-29	2007-09-13
2008	2008-05-16	2008-09-29
2009	2009-05-17	2009-09-28
2010	2010-06-28	2010-10-01
2011	2011-06-22	2011-09-24
2014	2014-05-27	2014-10-07
2015	2015-06-09	2015-10-14
2016	2016-06-03	2016-09-27
2017	2017-05-24	2017-09-12
2018	2018-06-04	2018-10-02
2019	2019-06-11	2019-09-15
2020	2020-05-28	2020-10-07
2021	2021-06-01	2021-09-26
2022	2022-05-26	2022-09-28
2023	2023-04-29	2023-10-20
2024	2024-06-06	2024-10-10
2025	2025-05-31	2025-09-24
2026	2026-03-19	2026-07-31

Every Fixed Threshold

Fixed thresholds at Hetch Hetchy
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	105	88	2024	45
35 C (95 F): Days	84	27	1913	5
40 C (104 F): Days	1	1	1933	1
90 F (32.2 C): Days	105	59	2024	23
100 F (37.8 C): Days	21	8	1913	2
0 C (32 F): Ice days (max	55	10	1937	1
0 C (32 F): Frost days (min	105	162	1912	14
-10 C (14 F): Days with min	48	21	1937	1
20 C (68 F): Tropical nights (min	30	11	1922	1
25 C (77 F): Days with min	1	2	1922	2
10 mm (0.39 in): Days with 10 mm or more rain	101	53	1983	13
25 mm (0.98 in): Days with 25 mm or more rain	101	25	1983	5
50 mm (1.97 in): Days with 50 mm or more rain	85	10	1982	2
100 mm (3.94 in): Days with 100 mm or more rain	10	2	1950	1
10 cm (3.9 in): Days with 10 cm or more snowfall	86	17	1933	3
25 cm (9.8 in): Days with 25 cm or more snowfall	50	7	1952	1
50 cm (19.7 in): Days with 50 cm or more snowfall	8	2	1935	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1911.

Download the Data

Data for Hetch Hetchy 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). Threshold counts are computed by this site.

Data as of 2026-10-12. Last revised 12 October 2026 (2026-10-12).

Hetch Hetchy Threshold Days by Year

Key Facts for Hetch Hetchy Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

Related