Helena AP ASOS Threshold Days by Year (USW00024144)

17 fixed thresholds counted per year at Helena AP ASOS (USW00024144): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Helena AP ASOS Thresholds

Helena AP ASOS: days with a maximum temperature at or above 30 C (86 F) in 88 years, most in 2017 with 71.
Helena AP ASOS: days with a maximum temperature at or above 90 F (32.2 C) in 88 years, most in 2022 with 54.
Helena AP ASOS: days with a maximum temperature at or below 0 C (32 F) in 88 years, most in 1985 with 85.
Helena AP ASOS: nights with a minimum temperature at or below 0 C (32 F) in 88 years, most in 1970 with 213.
17 fixed thresholds have at least one qualifying day at Helena AP ASOS.

Days at or above 30 C (86 F)

88 years with a qualifying day

Days per year at Helena AP ASOS with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 71 in 2017.

Days at or above 30 C (86 F) per year at Helena AP ASOS
Year	Days	Decade average
1939	50	50
1940	51	29.8
1941	24	29.8
1942	31	29.8
1943	28	29.8
1944	19	29.8
1945	39	29.8
1946	31	29.8
1947	27	29.8
1948	20	29.8
1949	28	29.8
1950	21	29.5
1951	22	29.5
1952	25	29.5
1953	34	29.5
1954	28	29.5
1955	33	29.5
1956	32	29.5
1957	30	29.5
1958	32	29.5
1959	38	29.5
1960	37	37.6
1961	49	37.6
1962	24	37.6
1963	33	37.6
1964	31	37.6
1965	26	37.6
1966	55	37.6
1967	55	37.6
1968	26	37.6
1969	40	37.6
1970	39	29
1971	31	29
1972	16	29
1973	35	29
1974	34	29
1975	13	29
1976	24	29
1977	29	29
1978	29	29
1979	40	29
1980	15	36.2
1981	41	36.2
1982	38	36.2
1983	31	36.2
1984	34	36.2
1985	38	36.2
1986	40	36.2
1987	29	36.2
1988	63	36.2
1989	33	36.2
1990	51	37.3
1991	48	37.3
1992	40	37.3
1993	9	37.3
1994	57	37.3
1995	26	37.3
1996	39	37.3
1997	22	37.3
1998	43	37.3
1999	38	37.3
2000	44	50.3
2001	64	50.3
2002	32	50.3
2003	62	50.3
2004	31	50.3
2005	46	50.3
2006	62	50.3
2007	64	50.3
2008	49	50.3
2009	49	50.3
2010	29	47.4
2011	48	47.4
2012	54	47.4
2013	56	47.4
2014	41	47.4
2015	53	47.4
2016	44	47.4
2017	71	47.4
2018	41	47.4
2019	37	47.4
2020	49	54
2021	69	54
2022	63	54
2023	48	54
2024	56	54
2025	45	54
2026	48	54

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

First to last qualifying date each year at Helena AP ASOS
Year	First date	Last date
1939	1939-04-28	1939-09-10
1940	1940-05-10	1940-09-11
1941	1941-06-22	1941-08-22
1942	1942-07-01	1942-09-08
1943	1943-07-06	1943-09-13
1944	1944-05-15	1944-09-08
1945	1945-06-21	1945-09-13
1946	1946-07-01	1946-09-30
1947	1947-05-02	1947-09-04
1948	1948-05-17	1948-09-14
1949	1949-06-09	1949-09-01
1950	1950-06-29	1950-09-06
1951	1951-07-05	1951-09-07
1952	1952-07-03	1952-09-26
1953	1953-06-11	1953-09-15
1954	1954-05-18	1954-08-30
1955	1955-06-22	1955-09-07
1956	1956-05-31	1956-09-26
1957	1957-06-04	1957-09-07
1958	1958-05-20	1958-09-11
1959	1959-06-12	1959-09-13
1960	1960-05-11	1960-09-19
1961	1961-05-26	1961-08-29
1962	1962-06-24	1962-08-26
1963	1963-06-18	1963-09-30
1964	1964-05-19	1964-08-18
1965	1965-06-10	1965-08-17
1966	1966-05-04	1966-09-23
1967	1967-05-21	1967-09-28
1968	1968-06-02	1968-09-10
1969	1969-06-04	1969-09-09
1970	1970-06-03	1970-08-31
1971	1971-06-22	1971-08-28
1972	1972-06-06	1972-08-28
1973	1973-06-08	1973-08-21
1974	1974-06-12	1974-08-05
1975	1975-07-04	1975-08-06
1976	1976-06-29	1976-09-05
1977	1977-06-01	1977-09-07
1978	1978-05-14	1978-09-07
1979	1979-06-11	1979-09-21
1980	1980-05-21	1980-09-05
1981	1981-06-26	1981-09-18
1982	1982-05-25	1982-09-09
1983	1983-06-23	1983-09-01
1984	1984-05-29	1984-09-18
1985	1985-06-07	1985-08-30
1986	1986-05-26	1986-08-28
1987	1987-05-07	1987-09-23
1988	1988-05-16	1988-09-06
1989	1989-06-29	1989-09-16
1990	1990-06-09	1990-09-25
1991	1991-07-03	1991-09-06
1992	1992-04-29	1992-09-23
1993	1993-05-11	1993-08-10
1994	1994-06-20	1994-09-27
1995	1995-07-07	1995-09-03
1996	1996-06-07	1996-08-30
1997	1997-06-04	1997-10-01
1998	1998-07-09	1998-09-17
1999	1999-05-24	1999-08-30
2000	2000-06-05	2000-09-17
2001	2001-05-12	2001-10-01
2002	2002-05-19	2002-09-15
2003	2003-05-24	2003-09-05
2004	2004-06-05	2004-09-11
2005	2005-06-20	2005-09-08
2006	2006-05-15	2006-09-12
2007	2007-05-18	2007-09-11
2008	2008-05-17	2008-09-16
2009	2009-05-18	2009-09-26
2010	2010-06-28	2010-09-28
2011	2011-06-22	2011-09-27
2012	2012-05-15	2012-09-09
2013	2013-05-12	2013-09-16
2014	2014-07-02	2014-09-25
2015	2015-06-07	2015-10-10
2016	2016-06-04	2016-09-01
2017	2017-05-05	2017-09-13
2018	2018-06-09	2018-09-10
2019	2019-06-13	2019-09-16
2020	2020-05-30	2020-09-12
2021	2021-05-17	2021-09-27
2022	2022-06-16	2022-09-11
2023	2023-05-20	2023-09-17
2024	2024-06-06	2024-10-04
2025	2025-05-10	2025-09-20
2026	2026-05-25	2026-09-25

Every Fixed Threshold

Fixed thresholds at Helena AP ASOS
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	88	71	2017	48
35 C (95 F): Days	80	26	2021	8
40 C (104 F): Days	4	2	2002	1
90 F (32.2 C): Days	88	54	2022	28
100 F (37.8 C): Days	31	9	2003	3
0 C (32 F): Ice days (max	88	85	1985	12
0 C (32 F): Frost days (min	88	213	1970	93
-10 C (14 F): Days with min	88	93	1985	15
-20 C (-4 F): Days with min	88	42	1949	1
-30 C (-22 F): Days with min	53	13	1950	1
-40 C (-40 F): Days with min	2	2	1957	1
20 C (68 F): Tropical nights (min	11	3	2021	1
10 mm (0.39 in): Days with 10 mm or more rain	86	19	1975	10
25 mm (0.98 in): Days with 25 mm or more rain	39	2	1944	1
50 mm (1.97 in): Days with 50 mm or more rain	1	1	1964	1
10 cm (3.9 in): Days with 10 cm or more snowfall	70	8	1967	1
25 cm (9.8 in): Days with 25 cm or more snowfall	9	1	1941	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1939.

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Data for Helena AP ASOS 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 2026-10-18. Last revised 18 October 2026 (2026-10-18).

Helena AP ASOS Threshold Days by Year (USW00024144)

Key Facts for Helena AP ASOS Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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