Boulder Threshold Days by Year (USC00050848)

20 fixed thresholds counted per year at Boulder (USC00050848): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Boulder Thresholds

Boulder: days with a maximum temperature at or above 30 C (86 F) in 122 years, most in 2012 with 88.
Boulder: days with a maximum temperature at or below 0 C (32 F) in 122 years, most in 1924 with 33.
Boulder: nights with a minimum temperature at or below 0 C (32 F) in 122 years, most in 1984 with 177.
Boulder: nights with a minimum temperature at or below -10 C (14 F) in 122 years, most in 1932 with 50.
20 fixed thresholds have at least one qualifying day at Boulder.

Days at or above 30 C (86 F)

122 years with a qualifying day

Days per year at Boulder with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 88 in 2012.

Days at or above 30 C (86 F) per year at Boulder
Year	Days	Decade average
1898	26	30
1899	34	30
1900	33	25.9
1901	39	25.9
1902	34	25.9
1903	25	25.9
1904	16	25.9
1905	24	25.9
1906	10	25.9
1907	24	25.9
1908	25	25.9
1909	29	25.9
1911	36	39.1
1913	26	39.1
1914	42	39.1
1915	13	39.1
1916	34	39.1
1917	54	39.1
1918	51	39.1
1919	57	39.1
1920	33	40.9
1921	46	40.9
1922	64	40.9
1923	17	40.9
1924	41	40.9
1925	43	40.9
1926	34	40.9
1927	27	40.9
1928	38	40.9
1929	66	40.9
1930	50	54.4
1931	73	54.4
1932	58	54.4
1933	60	54.4
1934	75	54.4
1935	52	54.4
1936	57	54.4
1937	43	54.4
1938	35	54.4
1939	41	54.4
1940	43	45.2
1941	18	45.2
1942	35	45.2
1943	58	45.2
1944	39	45.2
1945	30	45.2
1946	43	45.2
1948	79	45.2
1949	62	45.2
1950	52	67.5
1951	50	67.5
1952	77	67.5
1953	78	67.5
1954	80	67.5
1955	72	67.5
1956	78	67.5
1957	61	67.5
1958	64	67.5
1959	63	67.5
1960	71	56.2
1961	45	56.2
1962	57	56.2
1963	61	56.2
1964	70	56.2
1965	39	56.2
1966	67	56.2
1967	36	56.2
1968	52	56.2
1969	64	56.2
1970	50	52.7
1971	54	52.7
1972	41	52.7
1973	50	52.7
1974	57	52.7
1975	52	52.7
1976	48	52.7
1977	54	52.7
1978	68	52.7
1980	81	57.5
1981	53	57.5
1982	42	57.5
1984	64	57.5
1985	51	57.5
1986	44	57.5
1987	54	57.5
1988	71	57.5
1991	31	42.6
1992	25	42.6
1993	22	42.6
1994	63	42.6
1995	52	42.6
1996	52	42.6
1997	41	42.6
1998	56	42.6
1999	41	42.6
2000	79	62.5
2001	63	62.5
2002	81	62.5
2003	58	62.5
2004	33	62.5
2005	69	62.5
2006	67	62.5
2007	72	62.5
2008	60	62.5
2009	43	62.5
2010	70	68.6
2011	71	68.6
2012	88	68.6
2013	67	68.6
2014	46	68.6
2015	68	68.6
2016	70	68.6
2017	66	68.6
2018	73	68.6
2019	67	68.6
2020	83	76.4
2021	75	76.4
2022	78	76.4
2023	52	76.4
2024	86	76.4
2025	63	76.4
2026	98	76.4

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

First to last qualifying date each year at Boulder
Year	First date	Last date
1898	1898-06-20	1898-08-30
1899	1899-06-11	1899-10-01
1900	1900-06-20	1900-09-08
1901	1901-06-23	1901-09-20
1902	1902-06-09	1902-09-14
1903	1903-06-27	1903-09-03
1904	1904-07-12	1904-09-12
1905	1905-06-13	1905-09-23
1906	1906-06-16	1906-08-28
1907	1907-06-12	1907-09-11
1908	1908-05-19	1908-09-08
1909	1909-06-04	1909-09-02
1911	1911-06-07	1911-09-13
1913	1913-05-29	1913-08-27
1914	1914-06-13	1914-09-19
1915	1915-06-26	1915-09-22
1916	1916-05-06	1916-08-02
1917	1917-06-09	1917-08-30
1918	1918-06-10	1918-08-31
1919	1919-06-12	1919-09-01
1920	1920-05-29	1920-09-18
1921	1921-06-11	1921-10-05
1922	1922-06-07	1922-10-04
1923	1923-06-22	1923-09-05
1924	1924-06-11	1924-08-30
1925	1925-05-19	1925-09-16
1926	1926-05-23	1926-10-18
1927	1927-05-17	1927-09-05
1928	1928-05-30	1928-09-30
1929	1929-06-09	1929-10-09
1930	1930-05-21	1930-09-18
1931	1931-05-15	1931-09-29
1932	1932-05-22	1932-09-18
1933	1933-05-30	1933-09-29
1934	1934-05-18	1934-10-07
1935	1935-06-09	1935-09-22
1936	1936-06-12	1936-09-09
1937	1937-06-21	1937-09-20
1938	1938-05-28	1938-08-23
1939	1939-05-19	1939-09-22
1940	1940-05-31	1940-09-08
1941	1941-05-12	1941-09-04
1942	1942-05-25	1942-09-16
1943	1943-05-01	1943-09-18
1944	1944-06-19	1944-09-07
1945	1945-06-13	1945-09-06
1946	1946-06-04	1946-09-14
1948	1948-05-17	1948-10-13
1949	1949-05-27	1949-09-25
1950	1950-05-23	1950-10-20
1951	1951-05-28	1951-09-11
1952	1952-06-06	1952-09-27
1953	1953-06-09	1953-10-01
1954	1954-05-20	1954-09-22
1955	1955-05-30	1955-09-16
1956	1956-05-18	1956-10-07
1957	1957-06-04	1957-09-30
1958	1958-05-21	1958-09-22
1959	1959-06-05	1959-09-12
1960	1960-05-12	1960-09-12
1961	1961-05-10	1961-08-29
1962	1962-05-09	1962-10-10
1963	1963-05-06	1963-10-01
1964	1964-05-15	1964-10-01
1965	1965-06-22	1965-10-09
1966	1966-05-05	1966-09-24
1967	1967-05-23	1967-10-03
1968	1968-06-02	1968-09-11
1969	1969-05-25	1969-09-29
1970	1970-05-17	1970-09-11
1971	1971-06-16	1971-09-14
1972	1972-06-01	1972-09-18
1973	1973-06-07	1973-08-28
1974	1974-05-27	1974-09-11
1975	1975-06-24	1975-09-07
1976	1976-06-10	1976-09-07
1977	1977-05-23	1977-09-09
1978	1978-05-14	1978-10-01
1980	1980-06-03	1980-09-30
1981	1981-05-02	1981-09-28
1982	1982-06-28	1982-09-09
1984	1984-05-12	1984-09-19
1985	1985-05-28	1985-09-06
1986	1986-06-06	1986-08-29
1987	1987-06-05	1987-09-03
1988	1988-04-07	1988-09-17
1991	1991-06-17	1991-10-16
1992	1992-04-30	1992-09-23
1993	1993-06-12	1993-09-12
1994	1994-04-23	1994-09-29
1995	1995-06-13	1995-09-15
1996	1996-05-14	1996-10-11
1997	1997-06-01	1997-08-29
1998	1998-06-01	1998-09-28
1999	1999-06-07	1999-08-31
2000	2000-05-04	2000-09-17
2001	2001-06-02	2001-09-27
2002	2002-05-30	2002-09-08
2003	2003-05-29	2003-10-23
2004	2004-05-05	2004-09-18
2005	2005-05-20	2005-10-02
2006	2006-05-19	2006-09-14
2007	2007-06-10	2007-09-22
2008	2008-06-10	2008-09-26
2009	2009-06-29	2009-09-29
2010	2010-05-22	2010-09-28
2011	2011-05-08	2011-10-01
2012	2012-04-24	2012-09-23
2013	2013-05-17	2013-09-08
2014	2014-06-03	2014-09-26
2015	2015-05-31	2015-10-11
2016	2016-06-09	2016-09-19
2017	2017-06-09	2017-09-21
2018	2018-05-25	2018-09-23
2019	2019-06-13	2019-09-29
2020	2020-05-19	2020-10-06
2021	2021-06-04	2021-09-27
2022	2022-05-07	2022-09-20
2023	2023-06-19	2023-10-20
2024	2024-06-05	2024-10-10
2025	2025-06-10	2025-10-03
2026	2026-03-20	2026-10-09

Every Fixed Threshold

Fixed thresholds at Boulder
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	122	88	2012	98
35 C (95 F): Days	107	22	2007	28
40 C (104 F): Days	2	2	1954	1
90 F (32.2 C): Days	121	60	1952	57
100 F (37.8 C): Days	26	6	1954	7
0 C (32 F): Ice days (max	122	33	1924	5
0 C (32 F): Frost days (min	122	177	1984	57
-10 C (14 F): Days with min	122	50	1932	8
-20 C (-4 F): Days with min	91	10	1899	1
-30 C (-22 F): Days with min	4	1	1913	1
20 C (68 F): Tropical nights (min	83	24	1919	5
25 C (77 F): Days with min	2	1	1924	1
10 mm (0.39 in): Days with 10 mm or more rain	113	26	1995	7
25 mm (0.98 in): Days with 25 mm or more rain	106	9	1969	2
50 mm (1.97 in): Days with 50 mm or more rain	36	3	1942	1
100 mm (3.94 in): Days with 100 mm or more rain	1	1	2013	1
200 mm (7.87 in): Days with 200 mm or more rain	1	1	2013	1
10 cm (3.9 in): Days with 10 cm or more snowfall	95	15	1997	2
25 cm (9.8 in): Days with 25 cm or more snowfall	61	5	1909	1
50 cm (19.7 in): Days with 50 cm or more snowfall	3	1	1957	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1898.

Download the Data

Data for Boulder 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 2026-10-17. Last revised 17 October 2026 (2026-10-17).

Boulder Threshold Days by Year (USC00050848)

Key Facts for Boulder Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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