Helena Threshold Days by Year

20 fixed thresholds counted per year at Helena (USC00033242): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Helena Thresholds

Helena: days with 10 mm (0.39 in) or more of precipitation in 120 years, most in 1945 with 57.
Helena: days with 25 mm (0.98 in) or more of precipitation in 120 years, most in 2019 with 28.
Helena: days with 50 mm (1.97 in) or more of precipitation in 117 years, most in 1979 with 11.
Helena: nights with a minimum temperature at or below 0 C (32 F) in 101 years, most in 1968 with 90.
20 fixed thresholds have at least one qualifying day at Helena.

Days at or above 30 C (86 F)

99 years with a qualifying day

Days per year at Helena with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 167 in 2007.

Days at or above 30 C (86 F) per year at Helena
Year	Days	Decade average
1904	101	107.8
1905	101	107.8
1906	105	107.8
1907	110	107.8
1908	118	107.8
1909	112	107.8
1910	132	115.7
1911	116	115.7
1912	99	115.7
1925	157	129.8
1926	144	129.8
1927	138	129.8
1928	108	129.8
1929	102	129.8
1930	110	110.6
1931	123	110.6
1932	90	110.6
1933	113	110.6
1934	118	110.6
1935	98	110.6
1936	115	110.6
1937	110	110.6
1938	112	110.6
1939	117	110.6
1940	75	101.9
1941	126	101.9
1942	92	101.9
1943	106	101.9
1944	114	101.9
1945	89	101.9
1946	76	101.9
1947	117	101.9
1948	110	101.9
1949	114	101.9
1950	96	119.3
1951	118	119.3
1952	132	119.3
1953	140	119.3
1955	131	119.3
1956	122	119.3
1957	103	119.3
1958	109	119.3
1959	123	119.3
1960	113	101.5
1961	94	101.5
1962	121	101.5
1963	121	101.5
1964	103	101.5
1965	100	101.5
1966	93	101.5
1967	87	101.5
1968	91	101.5
1969	92	101.5
1970	98	90.7
1971	95	90.7
1972	105	90.7
1974	71	90.7
1975	84	90.7
1976	79	90.7
1977	109	90.7
1978	102	90.7
1979	73	90.7
1981	105	108.6
1982	113	108.6
1983	100	108.6
1984	93	108.6
1985	112	108.6
1986	121	108.6
1987	129	108.6
1988	112	108.6
1989	92	108.6
1990	106	108.3
1991	117	108.3
1992	90	108.3
1993	104	108.3
1994	98	108.3
1995	109	108.3
1997	108	108.3
1998	130	108.3
1999	113	108.3
2003	112	127.2
2004	100	127.2
2005	127	127.2
2006	126	127.2
2007	167	127.2
2008	131	127.2
2010	131	105.1
2011	118	105.1
2012	112	105.1
2013	99	105.1
2014	82	105.1
2015	102	105.1
2016	100	105.1
2017	90	105.1
2018	120	105.1
2019	97	105.1
2020	92	86
2024	105	86
2026	61	86

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

First to last qualifying date each year at Helena
Year	First date	Last date
1904	1904-05-10	1904-10-10
1905	1905-05-05	1905-10-07
1906	1906-04-10	1906-09-22
1907	1907-03-20	1907-10-07
1908	1908-03-18	1908-10-17
1909	1909-04-18	1909-11-04
1910	1910-03-23	1910-10-25
1911	1911-03-09	1911-10-06
1912	1912-05-08	1912-09-25
1925	1925-04-07	1925-10-06
1926	1926-04-17	1926-10-19
1927	1927-04-03	1927-10-28
1928	1928-03-29	1928-10-15
1929	1929-03-24	1929-10-19
1930	1930-04-10	1930-10-16
1931	1931-04-16	1931-11-10
1932	1932-04-22	1932-10-23
1933	1933-05-10	1933-09-30
1934	1934-05-04	1934-10-24
1935	1935-05-11	1935-10-16
1936	1936-04-14	1936-09-28
1937	1937-04-17	1937-11-01
1938	1938-05-01	1938-10-17
1939	1939-05-10	1939-10-23
1940	1940-05-08	1940-10-13
1941	1941-04-12	1941-10-23
1942	1942-05-28	1942-10-17
1943	1943-04-10	1943-09-16
1944	1944-05-11	1944-10-25
1945	1945-04-13	1945-09-28
1946	1946-05-30	1946-09-26
1947	1947-05-04	1947-10-22
1948	1948-04-08	1948-09-23
1949	1949-04-26	1949-10-11
1950	1950-04-28	1950-10-16
1951	1951-04-30	1951-10-06
1952	1952-04-28	1952-10-02
1953	1953-04-09	1953-10-22
1955	1955-04-18	1955-10-07
1956	1956-04-28	1956-10-11
1957	1957-04-29	1957-09-21
1958	1958-05-13	1958-09-26
1959	1959-04-30	1959-10-10
1960	1960-04-06	1960-10-04
1961	1961-05-21	1961-10-12
1962	1962-04-28	1962-10-16
1963	1963-03-31	1963-10-24
1964	1964-05-18	1964-09-24
1965	1965-04-23	1965-09-22
1966	1966-04-30	1966-10-10
1967	1967-04-06	1967-10-15
1968	1968-05-15	1968-10-15
1969	1969-05-22	1969-10-13
1970	1970-05-01	1970-10-03
1971	1971-05-24	1971-10-04
1972	1972-04-13	1972-10-17
1974	1974-05-11	1974-09-21
1975	1975-05-21	1975-10-15
1976	1976-05-13	1976-10-05
1977	1977-04-14	1977-10-02
1978	1978-04-08	1978-10-13
1979	1979-06-08	1979-10-22
1981	1981-04-27	1981-10-06
1982	1982-05-05	1982-10-09
1983	1983-06-03	1983-10-01
1984	1984-04-29	1984-09-26
1985	1985-05-07	1985-10-14
1986	1986-04-30	1986-10-05
1987	1987-04-20	1987-09-29
1988	1988-05-04	1988-11-05
1989	1989-04-23	1989-10-13
1990	1990-04-25	1990-10-04
1991	1991-05-13	1991-10-04
1992	1992-04-15	1992-10-14
1993	1993-05-07	1993-10-07
1994	1994-04-22	1994-10-05
1995	1995-04-10	1995-10-13
1997	1997-05-18	1997-10-12
1998	1998-05-08	1998-11-01
1999	1999-04-10	1999-10-14
2003	2003-04-15	2003-10-25
2004	2004-05-07	2004-10-29
2005	2005-05-12	2005-10-20
2006	2006-04-16	2006-10-19
2007	2007-03-30	2007-10-21
2008	2008-04-24	2008-10-08
2010	2010-04-22	2010-10-12
2011	2011-04-10	2011-10-19
2012	2012-04-29	2012-09-28
2013	2013-05-15	2013-09-20
2014	2014-05-05	2014-09-22
2015	2015-06-05	2015-10-16
2016	2016-05-25	2016-10-08
2017	2017-04-30	2017-10-15
2018	2018-05-08	2018-10-09
2019	2019-05-08	2019-10-11
2020	2020-06-03	2020-09-19
2024	2024-04-28	2024-10-28
2026	2026-03-23	2026-08-31

Every Fixed Threshold

Fixed thresholds at Helena
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	99	167	2007	61
35 C (95 F): Days	97	116	1925	30
40 C (104 F): Days	11	37	1925	1
45 C (113 F): Days	1	1	1925	1
90 F (32.2 C): Days	99	143	1925	52
100 F (37.8 C): Days	52	71	1925	6
110 F (43.3 C): Days	2	3	1925	2
0 C (32 F): Ice days (max	83	18	1989	4
0 C (32 F): Frost days (min	101	90	1968	26
-10 C (14 F): Days with min	78	15	1963	2
-20 C (-4 F): Days with min	3	1	1930	1
20 C (68 F): Tropical nights (min	101	136	2018	60
25 C (77 F): Days with min	65	30	1952	15
10 mm (0.39 in): Days with 10 mm or more rain	120	57	1945	20
25 mm (0.98 in): Days with 25 mm or more rain	120	28	2019	8
50 mm (1.97 in): Days with 50 mm or more rain	117	11	1979	1
100 mm (3.94 in): Days with 100 mm or more rain	37	3	1906	2
200 mm (7.87 in): Days with 200 mm or more rain	1	1	1893	1
10 cm (3.9 in): Days with 10 cm or more snowfall	10	1	1935	1
25 cm (9.8 in): Days with 25 cm or more snowfall	1	1	1963	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1904.

Download the Data

Data for Helena 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).

Helena Threshold Days by Year

Key Facts for Helena Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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