Mason City Threshold Days by Year (USC00135230)

19 fixed thresholds counted per year at Mason City (USC00135230): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Mason City Thresholds

Mason City: days with a maximum temperature at or above 30 C (86 F) in 123 years, most in 1921 with 65.
Mason City: days with a maximum temperature at or below 0 C (32 F) in 123 years, most in 1969 with 98.
Mason City: days with a maximum temperature at or above 90 F (32.2 C) in 121 years, most in 1936 with 48.
Mason City: nights with a minimum temperature at or below 0 C (32 F) in 121 years, most in 1952 with 182.
19 fixed thresholds have at least one qualifying day at Mason City.

Days at or above 30 C (86 F)

123 years with a qualifying day

Days per year at Mason City with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 65 in 1921.

Days at or above 30 C (86 F) per year at Mason City
Year	Days	Decade average
1895	47	35.7
1896	25	35.7
1898	35	35.7
1903	18	21.1
1904	11	21.1
1905	27	21.1
1906	27	21.1
1907	21	21.1
1908	21	21.1
1909	23	21.1
1910	44	39.9
1911	42	39.9
1912	26	39.9
1913	59	39.9
1914	43	39.9
1915	24	39.9
1916	43	39.9
1917	26	39.9
1919	52	39.9
1920	31	36
1921	65	36
1922	42	36
1923	42	36
1924	13	36
1925	43	36
1926	31	36
1927	39	36
1928	23	36
1929	31	36
1930	44	49.5
1931	64	49.5
1932	22	49.5
1933	60	49.5
1934	57	49.5
1935	45	49.5
1936	59	49.5
1937	53	49.5
1938	41	49.5
1939	50	49.5
1940	38	36.8
1941	47	36.8
1942	23	36.8
1943	31	36.8
1944	34	36.8
1945	22	36.8
1946	19	36.8
1947	57	36.8
1948	51	36.8
1949	46	36.8
1950	14	31.5
1951	11	31.5
1952	42	31.5
1953	35	31.5
1954	27	31.5
1955	61	31.5
1956	34	31.5
1957	29	31.5
1958	26	31.5
1959	36	31.5
1960	29	27.5
1961	28	27.5
1962	20	27.5
1963	33	27.5
1964	45	27.5
1965	25	27.5
1966	30	27.5
1967	17	27.5
1968	25	27.5
1969	23	27.5
1970	41	41.9
1971	32	41.9
1972	33	41.9
1974	37	41.9
1976	51	41.9
1977	57	41.9
1979	42	41.9
1980	55	43.3
1981	26	43.3
1982	25	43.3
1983	61	43.3
1984	41	43.3
1985	42	43.3
1986	32	43.3
1987	57	43.3
1988	65	43.3
1989	29	43.3
1990	19	20.5
1991	32	20.5
1992	8	20.5
1993	8	20.5
1994	16	20.5
1995	29	20.5
1996	13	20.5
1997	20	20.5
1998	33	20.5
1999	27	20.5
2000	20	23.9
2001	31	23.9
2002	41	23.9
2003	21	23.9
2004	8	23.9
2005	38	23.9
2006	26	23.9
2007	36	23.9
2008	9	23.9
2009	9	23.9
2010	31	27.3
2011	31	27.3
2012	49	27.3
2013	29	27.3
2014	10	27.3
2015	20	27.3
2016	20	27.3
2017	28	27.3
2018	32	27.3
2019	23	27.3
2020	41	36
2021	46	36
2022	27	36
2023	43	36
2024	31	36
2025	32	36
2026	32	36

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

First to last qualifying date each year at Mason City
Year	First date	Last date
1895	1895-04-30	1895-09-21
1896	1896-05-24	1896-08-10
1898	1898-06-03	1898-09-29
1903	1903-06-26	1903-08-24
1904	1904-05-22	1904-09-28
1905	1905-06-04	1905-08-29
1906	1906-06-06	1906-09-10
1907	1907-05-12	1907-08-31
1908	1908-06-22	1908-09-21
1909	1909-05-05	1909-08-27
1910	1910-04-28	1910-09-17
1911	1911-05-09	1911-09-04
1912	1912-06-25	1912-09-09
1913	1913-05-01	1913-09-07
1914	1914-05-25	1914-09-18
1915	1915-05-11	1915-09-06
1916	1916-06-29	1916-09-06
1917	1917-05-17	1917-08-26
1919	1919-05-28	1919-10-03
1920	1920-05-22	1920-09-25
1921	1921-05-20	1921-09-09
1922	1922-05-10	1922-10-04
1923	1923-06-01	1923-09-05
1924	1924-04-23	1924-08-30
1925	1925-04-22	1925-09-19
1926	1926-05-01	1926-09-21
1927	1927-06-08	1927-09-17
1928	1928-05-09	1928-10-10
1929	1929-06-10	1929-09-03
1930	1930-04-10	1930-09-22
1931	1931-05-26	1931-09-20
1932	1932-05-14	1932-08-30
1933	1933-06-01	1933-09-25
1934	1934-05-05	1934-08-19
1935	1935-06-12	1935-09-24
1936	1936-05-16	1936-09-22
1937	1937-05-30	1937-09-23
1938	1938-06-14	1938-10-09
1939	1939-04-24	1939-09-22
1940	1940-05-12	1940-09-21
1941	1941-05-19	1941-09-21
1942	1942-05-29	1942-09-16
1943	1943-05-28	1943-08-31
1944	1944-05-14	1944-09-17
1945	1945-06-22	1945-09-07
1946	1946-06-07	1946-09-05
1947	1947-06-09	1947-10-21
1948	1948-05-20	1948-09-19
1949	1949-04-25	1949-08-26
1950	1950-06-13	1950-08-24
1951	1951-07-07	1951-10-01
1952	1952-04-29	1952-09-30
1953	1953-05-29	1953-10-15
1954	1954-06-11	1954-09-18
1955	1955-05-02	1955-09-20
1956	1956-05-13	1956-10-12
1957	1957-06-17	1957-09-01
1958	1958-06-04	1958-10-15
1959	1959-05-02	1959-09-08
1960	1960-04-22	1960-09-07
1961	1961-05-31	1961-09-10
1962	1962-05-05	1962-09-12
1963	1963-05-08	1963-10-06
1964	1964-04-16	1964-09-09
1965	1965-06-12	1965-08-25
1966	1966-05-26	1966-09-01
1967	1967-05-18	1967-08-16
1968	1968-06-03	1968-08-23
1969	1969-05-27	1969-08-30
1970	1970-04-28	1970-09-20
1971	1971-06-04	1971-09-30
1972	1972-05-16	1972-09-16
1974	1974-06-03	1974-09-27
1976	1976-06-06	1976-10-02
1977	1977-04-27	1977-09-08
1979	1979-05-17	1979-09-05
1980	1980-04-21	1980-09-12
1981	1981-06-05	1981-09-11
1982	1982-05-04	1982-09-12
1983	1983-06-10	1983-09-10
1984	1984-06-01	1984-09-20
1985	1985-04-17	1985-09-20
1986	1986-05-05	1986-09-26
1987	1987-05-09	1987-09-06
1988	1988-05-15	1988-09-18
1989	1989-05-30	1989-08-23
1990	1990-05-08	1990-09-13
1991	1991-04-07	1991-08-31
1992	1992-05-01	1992-10-03
1993	1993-06-24	1993-09-13
1994	1994-04-19	1994-09-20
1995	1995-06-17	1995-08-31
1996	1996-05-18	1996-08-07
1997	1997-06-16	1997-10-07
1998	1998-05-15	1998-09-27
1999	1999-06-06	1999-09-08
2000	2000-06-09	2000-09-19
2001	2001-05-15	2001-08-09
2002	2002-04-16	2002-10-01
2003	2003-04-15	2003-09-08
2004	2004-04-17	2004-09-02
2005	2005-06-07	2005-10-05
2006	2006-04-14	2006-10-04
2007	2007-04-30	2007-10-07
2008	2008-06-08	2008-07-31
2009	2009-04-25	2009-08-15
2010	2010-05-25	2010-10-10
2011	2011-05-11	2011-09-13
2012	2012-05-19	2012-09-12
2013	2013-05-15	2013-09-11
2014	2014-05-31	2014-09-05
2015	2015-06-10	2015-09-16
2016	2016-05-07	2016-09-07
2017	2017-06-03	2017-09-25
2018	2018-05-25	2018-09-21
2019	2019-06-01	2019-10-01
2020	2020-06-02	2020-09-26
2021	2021-05-02	2021-09-27
2022	2022-05-10	2022-09-21
2023	2023-04-13	2023-10-03
2024	2024-05-19	2024-10-06
2025	2025-06-03	2025-10-05
2026	2026-05-16	2026-10-13

Every Fixed Threshold

Fixed thresholds at Mason City
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	123	65	1921	32
35 C (95 F): Days	83	25	1913	6
40 C (104 F): Days	5	7	1936	1
90 F (32.2 C): Days	121	48	1936	11
100 F (37.8 C): Days	26	14	1936	1
0 C (32 F): Ice days (max	123	98	1969	36
0 C (32 F): Frost days (min	121	182	1952	91
-10 C (14 F): Days with min	121	93	1989	33
-20 C (-4 F): Days with min	121	41	1917	11
-30 C (-22 F): Days with min	53	9	1936	3
-40 C (-40 F): Days with min	1	1	1996	1
20 C (68 F): Tropical nights (min	120	28	1988	16
25 C (77 F): Days with min	16	4	1988	1
10 mm (0.39 in): Days with 10 mm or more rain	121	46	2018	23
25 mm (0.98 in): Days with 25 mm or more rain	121	18	1990	6
50 mm (1.97 in): Days with 50 mm or more rain	92	7	2018	2
100 mm (3.94 in): Days with 100 mm or more rain	14	1	1896	1
10 cm (3.9 in): Days with 10 cm or more snowfall	79	8	1951	3
25 cm (9.8 in): Days with 25 cm or more snowfall	17	2	1934	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1895.

Download the Data

Data for Mason City 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).

Mason City Threshold Days by Year (USC00135230)

Key Facts for Mason City Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

Related