Boulder Threshold Days by Year

15 fixed thresholds counted per year at Boulder (USC00420849): 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 72 years, most in 2002 with 60.
Boulder: days with a maximum temperature at or below 0 C (32 F) in 72 years, most in 2008 with 32.
Boulder: nights with a minimum temperature at or below 0 C (32 F) in 71 years, most in 1970 with 192.
Boulder: nights with a minimum temperature at or below -10 C (14 F) in 71 years, most in 1960 with 57.
15 fixed thresholds have at least one qualifying day at Boulder.

Days at or above 30 C (86 F)

72 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 60 in 2002.

Days at or above 30 C (86 F) per year at Boulder
Year	Days	Decade average
1955	29	32.8
1956	34	32.8
1957	22	32.8
1958	38	32.8
1959	41	32.8
1960	51	28.7
1961	35	28.7
1962	24	28.7
1963	24	28.7
1964	28	28.7
1965	16	28.7
1966	32	28.7
1967	28	28.7
1968	20	28.7
1969	29	28.7
1970	31	32
1971	41	32
1972	34	32
1973	36	32
1974	38	32
1975	25	32
1976	19	32
1977	35	32
1978	24	32
1979	37	32
1980	31	26
1981	43	26
1982	20	26
1983	11	26
1984	27	26
1985	36	26
1986	25	26
1987	12	26
1988	29	26
1989	26	26
1990	40	27.8
1991	24	27.8
1992	15	27.8
1993	10	27.8
1994	51	27.8
1995	32	27.8
1996	51	27.8
1997	16	27.8
1998	24	27.8
1999	15	27.8
2000	49	29.4
2001	30	29.4
2002	60	29.4
2003	34	29.4
2004	12	29.4
2005	15	29.4
2006	21	29.4
2007	30	29.4
2008	25	29.4
2009	18	29.4
2010	15	23.9
2011	11	23.9
2012	20	23.9
2013	20	23.9
2014	20	23.9
2015	21	23.9
2016	24	23.9
2017	35	23.9
2018	40	23.9
2019	33	23.9
2020	49	34.3
2021	41	34.3
2022	28	34.3
2023	28	34.3
2024	17	34.3
2025	31	34.3
2026	46	34.3

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
1955	1955-06-07	1955-09-07
1956	1956-06-11	1956-09-19
1957	1957-06-05	1957-09-08
1958	1958-06-18	1958-09-01
1959	1959-06-16	1959-09-09
1960	1960-06-03	1960-08-30
1961	1961-06-13	1961-08-22
1962	1962-06-20	1962-09-18
1963	1963-07-01	1963-08-16
1964	1964-06-25	1964-08-25
1965	1965-07-04	1965-08-14
1966	1966-06-26	1966-08-18
1967	1967-06-30	1967-08-26
1968	1968-06-17	1968-09-07
1969	1969-07-01	1969-08-26
1970	1970-06-21	1970-08-30
1971	1971-06-15	1971-09-12
1972	1972-06-29	1972-08-23
1973	1973-06-08	1973-08-20
1974	1974-06-12	1974-09-10
1975	1975-06-13	1975-08-10
1976	1976-06-27	1976-08-25
1977	1977-06-23	1977-09-09
1978	1978-06-21	1978-09-04
1979	1979-06-24	1979-09-09
1980	1980-06-27	1980-08-13
1981	1981-06-07	1981-08-27
1982	1982-06-27	1982-09-03
1983	1983-07-05	1983-09-16
1984	1984-05-29	1984-09-09
1985	1985-06-07	1985-08-31
1986	1986-06-22	1986-08-27
1987	1987-06-13	1987-08-19
1988	1988-06-21	1988-09-08
1989	1989-06-15	1989-08-13
1990	1990-06-04	1990-09-14
1991	1991-07-01	1991-08-30
1992	1992-06-22	1992-08-20
1993	1993-06-14	1993-08-02
1994	1994-06-12	1994-08-27
1995	1995-06-26	1995-09-03
1996	1996-05-12	1996-09-04
1997	1997-05-31	1997-08-20
1998	1998-06-28	1998-08-30
1999	1999-06-19	1999-07-24
2000	2000-05-22	2000-09-17
2001	2001-06-08	2001-09-06
2002	2002-05-29	2002-08-26
2003	2003-05-28	2003-08-19
2004	2004-06-05	2004-08-13
2005	2005-07-03	2005-07-29
2006	2006-06-03	2006-07-28
2007	2007-06-14	2007-08-26
2008	2008-05-19	2008-08-27
2009	2009-06-30	2009-08-29
2010	2010-06-04	2010-07-27
2011	2011-06-28	2011-08-25
2012	2012-06-17	2012-08-30
2013	2013-06-08	2013-08-16
2014	2014-06-28	2014-08-17
2015	2015-06-18	2015-08-24
2016	2016-06-03	2016-07-30
2017	2017-06-16	2017-09-05
2018	2018-06-04	2018-09-09
2019	2019-07-10	2019-09-04
2020	2020-05-27	2020-09-07
2021	2021-06-04	2021-08-28
2022	2022-06-07	2022-09-09
2023	2023-07-02	2023-08-30
2024	2024-06-06	2024-08-07
2025	2025-05-31	2025-08-22
2026	2026-06-13	2026-09-10

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	72	60	2002	46
35 C (95 F): Days	15	6	2002	1
90 F (32.2 C): Days	65	33	2002	19
0 C (32 F): Ice days (max	72	32	2008	1
0 C (32 F): Frost days (min	71	192	1970	63
-10 C (14 F): Days with min	71	57	1960	4
-20 C (-4 F): Days with min	19	5	1971	1
20 C (68 F): Tropical nights (min	46	17	2020	10
25 C (77 F): Days with min	1	1	2021	1
10 mm (0.39 in): Days with 10 mm or more rain	71	20	1957	2
25 mm (0.98 in): Days with 25 mm or more rain	40	4	2004	1
50 mm (1.97 in): Days with 50 mm or more rain	4	1	1960	1
10 cm (3.9 in): Days with 10 cm or more snowfall	51	14	2010	2
25 cm (9.8 in): Days with 25 cm or more snowfall	14	2	1993	1
50 cm (19.7 in): Days with 50 cm or more snowfall	1	1	2010	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1955.

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 2026-10-14 (14 October 2026). Threshold counts are computed by this site.

Data as of 2026-10-14. Last revised 14 October 2026 (2026-10-14).

Boulder Threshold Days by Year

Key Facts for Boulder Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

Related