Mt Hamilton Threshold Days by Year (USC00045933)
15 fixed thresholds counted per year at Mt Hamilton (USC00045933): hot days, frost, tropical nights and heavy rain, with the most days in a year.
Key Facts for Mt Hamilton Thresholds
- Mt Hamilton: days with 10 mm (0.39 in) or more of precipitation in 73 years, most in 1996 with 38.
- Mt Hamilton: days with 25 mm (0.98 in) or more of precipitation in 69 years, most in 1996 with 14.
- Mt Hamilton: days with a maximum temperature at or above 30 C (86 F) in 65 years, most in 1988 with 40.
- Mt Hamilton: nights with a minimum temperature at or below 0 C (32 F) in 64 years, most in 1952 with 100.
- 15 fixed thresholds have at least one qualifying day at Mt Hamilton.
Days at or above 30 C (86 F)
65 years with a qualifying day| Year | Days | Decade average |
|---|---|---|
| 1951 | 16 | 13.6 |
| 1952 | 12 | 13.6 |
| 1953 | 18 | 13.6 |
| 1954 | 12 | 13.6 |
| 1955 | 18 | 13.6 |
| 1956 | 12 | 13.6 |
| 1957 | 12 | 13.6 |
| 1958 | 9 | 13.6 |
| 1963 | 7 | 13 |
| 1968 | 13 | 13 |
| 1969 | 19 | 13 |
| 1970 | 20 | 17.2 |
| 1971 | 15 | 17.2 |
| 1972 | 14 | 17.2 |
| 1973 | 20 | 17.2 |
| 1975 | 13 | 17.2 |
| 1976 | 17 | 17.2 |
| 1977 | 17 | 17.2 |
| 1978 | 20 | 17.2 |
| 1979 | 19 | 17.2 |
| 1980 | 23 | 16.3 |
| 1981 | 24 | 16.3 |
| 1982 | 9 | 16.3 |
| 1983 | 12 | 16.3 |
| 1984 | 24 | 16.3 |
| 1986 | 1 | 16.3 |
| 1987 | 10 | 16.3 |
| 1988 | 40 | 16.3 |
| 1989 | 4 | 16.3 |
| 1990 | 11 | 10.1 |
| 1991 | 8 | 10.1 |
| 1992 | 8 | 10.1 |
| 1993 | 7 | 10.1 |
| 1994 | 7 | 10.1 |
| 1995 | 10 | 10.1 |
| 1996 | 21 | 10.1 |
| 1997 | 4 | 10.1 |
| 1998 | 19 | 10.1 |
| 1999 | 6 | 10.1 |
| 2000 | 7 | 11.5 |
| 2001 | 12 | 11.5 |
| 2002 | 12 | 11.5 |
| 2003 | 14 | 11.5 |
| 2004 | 3 | 11.5 |
| 2005 | 12 | 11.5 |
| 2006 | 19 | 11.5 |
| 2007 | 7 | 11.5 |
| 2008 | 12 | 11.5 |
| 2009 | 17 | 11.5 |
| 2010 | 8 | 16.6 |
| 2012 | 15 | 16.6 |
| 2013 | 10 | 16.6 |
| 2014 | 15 | 16.6 |
| 2015 | 15 | 16.6 |
| 2016 | 19 | 16.6 |
| 2017 | 29 | 16.6 |
| 2018 | 26 | 16.6 |
| 2019 | 12 | 16.6 |
| 2020 | 19 | 22.3 |
| 2021 | 30 | 22.3 |
| 2022 | 26 | 22.3 |
| 2023 | 14 | 22.3 |
| 2024 | 39 | 22.3 |
| 2025 | 14 | 22.3 |
| 2026 | 14 | 22.3 |
| Year | First date | Last date |
|---|---|---|
| 1951 | 1951-05-26 | 1951-09-15 |
| 1952 | 1952-07-15 | 1952-09-02 |
| 1953 | 1953-07-05 | 1953-09-14 |
| 1954 | 1954-06-21 | 1954-08-02 |
| 1955 | 1955-06-08 | 1955-09-11 |
| 1956 | 1956-06-26 | 1956-09-03 |
| 1957 | 1957-06-23 | 1957-09-08 |
| 1958 | 1958-07-10 | 1958-09-06 |
| 1963 | 1963-06-16 | 1963-10-01 |
| 1968 | 1968-06-25 | 1968-09-28 |
| 1969 | 1969-07-06 | 1969-09-02 |
| 1970 | 1970-06-01 | 1970-10-03 |
| 1971 | 1971-07-16 | 1971-09-16 |
| 1972 | 1972-06-29 | 1972-08-10 |
| 1973 | 1973-06-07 | 1973-08-15 |
| 1975 | 1975-06-13 | 1975-09-24 |
| 1976 | 1976-05-12 | 1976-09-09 |
| 1977 | 1977-06-05 | 1977-09-08 |
| 1978 | 1978-06-06 | 1978-10-13 |
| 1979 | 1979-07-13 | 1979-09-16 |
| 1980 | 1980-07-23 | 1980-10-07 |
| 1981 | 1981-06-04 | 1981-09-11 |
| 1982 | 1982-05-24 | 1982-08-24 |
| 1983 | 1983-07-11 | 1983-09-15 |
| 1984 | 1984-05-27 | 1984-09-16 |
| 1986 | 1986-07-30 | 1986-07-30 |
| 1987 | 1987-07-15 | 1987-10-05 |
| 1988 | 1988-06-18 | 1988-09-30 |
| 1989 | 1989-06-22 | 1989-09-12 |
| 1990 | 1990-06-20 | 1990-08-10 |
| 1991 | 1991-07-02 | 1991-09-24 |
| 1992 | 1992-08-10 | 1992-08-19 |
| 1993 | 1993-06-25 | 1993-09-27 |
| 1994 | 1994-07-12 | 1994-08-20 |
| 1995 | 1995-06-25 | 1995-08-03 |
| 1996 | 1996-07-01 | 1996-10-08 |
| 1997 | 1997-08-05 | 1997-08-08 |
| 1998 | 1998-07-16 | 1998-09-03 |
| 1999 | 1999-06-30 | 1999-08-26 |
| 2000 | 2000-06-14 | 2000-09-19 |
| 2001 | 2001-05-31 | 2001-10-01 |
| 2002 | 2002-07-09 | 2002-09-02 |
| 2003 | 2003-07-17 | 2003-09-27 |
| 2004 | 2004-08-11 | 2004-09-08 |
| 2005 | 2005-07-14 | 2005-08-07 |
| 2006 | 2006-06-22 | 2006-09-06 |
| 2007 | 2007-07-04 | 2007-09-01 |
| 2008 | 2008-06-21 | 2008-09-06 |
| 2009 | 2009-06-28 | 2009-09-27 |
| 2010 | 2010-06-28 | 2010-09-29 |
| 2012 | 2012-06-16 | 2012-10-02 |
| 2013 | 2013-06-07 | 2013-08-19 |
| 2014 | 2014-06-08 | 2014-09-13 |
| 2015 | 2015-06-26 | 2015-09-20 |
| 2016 | 2016-06-26 | 2016-09-19 |
| 2017 | 2017-06-18 | 2017-09-03 |
| 2018 | 2018-07-06 | 2018-09-27 |
| 2019 | 2019-06-10 | 2019-09-04 |
| 2020 | 2020-05-28 | 2020-10-01 |
| 2021 | 2021-06-17 | 2021-09-09 |
| 2022 | 2022-06-10 | 2022-09-09 |
| 2023 | 2023-06-30 | 2023-08-17 |
| 2024 | 2024-06-11 | 2024-10-06 |
| 2025 | 2025-05-30 | 2025-09-01 |
| 2026 | 2026-08-01 | 2026-10-04 |
Every Fixed Threshold
| Threshold | Years with a qualifying day | Most days in a year | Year | Latest year days |
|---|---|---|---|---|
| 30 C (86 F): Days | 65 | 40 | 1988 | 14 |
| 35 C (95 F): Days | 15 | 4 | 1955 | 3 |
| 90 F (32.2 C): Days | 58 | 21 | 1988 | 4 |
| 100 F (37.8 C): Days | 3 | 1 | 1972 | 1 |
| 0 C (32 F): Ice days (max | 57 | 19 | 1955 | 2 |
| 0 C (32 F): Frost days (min | 64 | 100 | 1952 | 8 |
| -10 C (14 F): Days with min | 4 | 2 | 1972 | 1 |
| 20 C (68 F): Tropical nights (min | 64 | 70 | 2024 | 43 |
| 25 C (77 F): Days with min | 51 | 13 | 1998 | 1 |
| 10 mm (0.39 in): Days with 10 mm or more rain | 73 | 38 | 1996 | 9 |
| 25 mm (0.98 in): Days with 25 mm or more rain | 69 | 14 | 1996 | 2 |
| 50 mm (1.97 in): Days with 50 mm or more rain | 30 | 3 | 1996 | 1 |
| 100 mm (3.94 in): Days with 100 mm or more rain | 3 | 2 | 1955 | 1 |
| 10 cm (3.9 in): Days with 10 cm or more snowfall | 33 | 6 | 1955 | 3 |
| 25 cm (9.8 in): Days with 25 cm or more snowfall | 8 | 1 | 1955 | 1 |
Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1951.
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 (2026-10-17).