Boulder Threshold Days by Year (USC00241008)

14 fixed thresholds counted per year at Boulder (USC00241008): 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 69 years, most in 1988 with 52.
Boulder: days with a maximum temperature at or below 0 C (32 F) in 69 years, most in 1955 with 82.
Boulder: nights with a minimum temperature at or below 0 C (32 F) in 68 years, most in 1960 with 234.
Boulder: nights with a minimum temperature at or below -10 C (14 F) in 68 years, most in 1985 with 106.
14 fixed thresholds have at least one qualifying day at Boulder.

Days at or above 30 C (86 F)

69 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 52 in 1988.

Days at or above 30 C (86 F) per year at Boulder
Year	Days	Decade average
1949	26	26
1950	13	26.6
1951	25	26.6
1952	20	26.6
1953	37	26.6
1954	29	26.6
1955	35	26.6
1956	26	26.6
1957	29	26.6
1958	22	26.6
1959	30	26.6
1960	35	28.3
1961	44	28.3
1962	6	28.3
1963	29	28.3
1964	9	28.3
1966	34	28.3
1967	33	28.3
1969	36	28.3
1970	40	28.2
1971	38	28.2
1972	19	28.2
1973	36	28.2
1974	36	28.2
1975	17	28.2
1976	21	28.2
1977	18	28.2
1978	21	28.2
1979	36	28.2
1980	10	30.8
1981	38	30.8
1982	26	30.8
1983	25	30.8
1984	33	30.8
1985	38	30.8
1986	32	30.8
1987	26	30.8
1988	52	30.8
1989	28	30.8
1990	34	28.2
1991	40	28.2
1992	24	28.2
1993	3	28.2
1994	45	28.2
1995	25	28.2
1996	35	28.2
1997	10	28.2
1998	39	28.2
1999	27	28.2
2000	32	31
2001	34	31
2002	20	31
2003	46	31
2004	16	31
2005	35	31
2006	36	31
2007	46	31
2008	25	31
2009	20	31
2010	11	30.4
2011	25	30.4
2012	47	30.4
2013	40	30.4
2014	23	30.4
2015	26	30.4
2016	29	30.4
2017	42	30.4
2024	30	24
2026	18	24

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
1949	1949-07-01	1949-09-20
1950	1950-05-22	1950-09-06
1951	1951-07-13	1951-08-21
1952	1952-07-04	1952-08-25
1953	1953-06-11	1953-09-15
1954	1954-05-18	1954-09-11
1955	1955-06-22	1955-09-07
1956	1956-06-08	1956-09-20
1957	1957-06-04	1957-09-07
1958	1958-06-27	1958-09-08
1959	1959-06-14	1959-09-13
1960	1960-06-24	1960-08-22
1961	1961-06-16	1961-08-25
1962	1962-06-25	1962-08-20
1963	1963-07-02	1963-09-29
1964	1964-08-03	1964-08-18
1966	1966-06-27	1966-09-23
1967	1967-07-05	1967-09-30
1969	1969-06-04	1969-09-03
1970	1970-06-04	1970-08-29
1971	1971-06-21	1971-08-29
1972	1972-07-08	1972-08-29
1973	1973-06-22	1973-08-30
1974	1974-06-14	1974-08-19
1975	1975-07-02	1975-08-07
1976	1976-06-30	1976-09-05
1977	1977-06-02	1977-08-20
1978	1978-06-28	1978-09-04
1979	1979-06-12	1979-09-16
1980	1980-07-21	1980-09-07
1981	1981-06-26	1981-09-19
1982	1982-07-19	1982-09-20
1983	1983-07-05	1983-09-02
1984	1984-05-29	1984-09-19
1985	1985-06-07	1985-08-30
1986	1986-05-27	1986-08-29
1987	1987-06-13	1987-09-02
1988	1988-05-16	1988-09-07
1989	1989-06-29	1989-08-12
1990	1990-06-22	1990-09-12
1991	1991-07-03	1991-09-07
1992	1992-06-10	1992-10-02
1993	1993-06-20	1993-07-30
1994	1994-06-20	1994-09-24
1995	1995-07-08	1995-09-04
1996	1996-06-08	1996-08-31
1997	1997-07-15	1997-08-28
1998	1998-07-13	1998-09-16
1999	1999-07-07	1999-08-30
2000	2000-06-07	2000-09-16
2001	2001-06-22	2001-09-25
2002	2002-06-25	2002-07-25
2003	2003-05-28	2003-09-05
2004	2004-07-14	2004-09-02
2005	2005-06-22	2005-09-09
2006	2006-06-27	2006-09-06
2007	2007-06-22	2007-09-05
2008	2008-06-21	2008-08-26
2009	2009-05-18	2009-09-20
2010	2010-07-16	2010-08-27
2011	2011-06-28	2011-08-29
2012	2012-06-23	2012-09-10
2013	2013-06-18	2013-09-02
2014	2014-07-03	2014-09-25
2015	2015-06-08	2015-09-13
2016	2016-06-07	2016-09-01
2017	2017-06-20	2017-09-13
2024	2024-06-23	2024-09-26
2026	2026-07-05	2026-08-24

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	69	52	1988	18
35 C (95 F): Days	33	11	2003	3
90 F (32.2 C): Days	67	29	2007	9
100 F (37.8 C): Days	2	2	2002	2
0 C (32 F): Ice days (max	69	82	1955	1
0 C (32 F): Frost days (min	68	234	1960	66
-10 C (14 F): Days with min	68	106	1985	12
-20 C (-4 F): Days with min	68	40	1949	2
-30 C (-22 F): Days with min	54	13	1972	3
-40 C (-40 F): Days with min	2	1	1983	1
10 mm (0.39 in): Days with 10 mm or more rain	68	11	1975	3
25 mm (0.98 in): Days with 25 mm or more rain	28	2	1971	1
10 cm (3.9 in): Days with 10 cm or more snowfall	25	7	1967	3
25 cm (9.8 in): Days with 25 cm or more snowfall	3	1	1950	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1949.

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 (USC00241008)

Key Facts for Boulder Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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