Iowa City Threshold Days by Year (USC00134101)

18 fixed thresholds counted per year at Iowa City (USC00134101): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Iowa City Thresholds

Iowa City: days with a maximum temperature at or above 30 C (86 F) in 129 years, most in 1901 with 93.
Iowa City: days with a maximum temperature at or above 90 F (32.2 C) in 129 years, most in 1988 with 63.
Iowa City: days with a maximum temperature at or below 0 C (32 F) in 129 years, most in 1978 with 72.
Iowa City: nights with a minimum temperature at or below 0 C (32 F) in 129 years, most in 1952 with 168.
18 fixed thresholds have at least one qualifying day at Iowa City.

Days at or above 30 C (86 F)

129 years with a qualifying day

Days per year at Iowa City with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 93 in 1901.

Days at or above 30 C (86 F) per year at Iowa City
Year	Days	Decade average
1893	49	63.3
1894	70	63.3
1895	75	63.3
1896	58	63.3
1897	69	63.3
1898	56	63.3
1899	66	63.3
1900	69	54.2
1901	93	54.2
1902	38	54.2
1903	33	54.2
1904	38	54.2
1905	37	54.2
1906	67	54.2
1907	49	54.2
1908	61	54.2
1909	57	54.2
1910	50	48.3
1911	57	48.3
1912	43	48.3
1913	66	48.3
1914	62	48.3
1915	22	48.3
1916	54	48.3
1917	28	48.3
1918	37	48.3
1919	64	48.3
1920	44	45
1921	68	45
1922	51	45
1923	54	45
1924	22	45
1925	56	45
1926	38	45
1927	42	45
1928	34	45
1929	41	45
1930	65	63.1
1931	70	63.1
1932	48	63.1
1933	69	63.1
1934	78	63.1
1935	61	63.1
1936	82	63.1
1937	61	63.1
1938	47	63.1
1939	50	63.1
1940	52	43.6
1941	52	43.6
1942	45	43.6
1943	49	43.6
1944	50	43.6
1945	31	43.6
1946	26	43.6
1952	64	58.6
1953	62	58.6
1954	65	58.6
1955	69	58.6
1956	64	58.6
1957	54	58.6
1958	26	58.6
1959	65	58.6
1960	42	48.9
1961	49	48.9
1962	45	48.9
1963	54	48.9
1964	56	48.9
1965	38	48.9
1966	55	48.9
1967	34	48.9
1968	59	48.9
1969	57	48.9
1970	65	60.6
1971	72	60.6
1972	57	60.6
1973	54	60.6
1974	39	60.6
1975	68	60.6
1976	63	60.6
1977	67	60.6
1978	60	60.6
1979	61	60.6
1980	79	62.7
1981	42	62.7
1982	40	62.7
1983	84	62.7
1984	62	62.7
1985	58	62.7
1986	50	62.7
1987	78	62.7
1988	87	62.7
1989	47	62.7
1990	44	48.4
1991	76	48.4
1992	18	48.4
1993	34	48.4
1994	52	48.4
1995	66	48.4
1996	40	48.4
1997	45	48.4
1998	56	48.4
1999	53	48.4
2000	47	53.2
2001	50	53.2
2002	64	53.2
2003	55	53.2
2004	40	53.2
2005	79	53.2
2006	59	53.2
2007	81	53.2
2008	36	53.2
2009	21	53.2
2010	75	52.8
2011	62	52.8
2012	88	52.8
2013	54	52.8
2014	24	52.8
2015	31	52.8
2016	49	52.8
2017	45	52.8
2018	53	52.8
2019	47	52.8
2020	51	53
2021	59	53
2022	47	53
2023	55	53
2024	53	53
2025	54	53
2026	52	53

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

First to last qualifying date each year at Iowa City
Year	First date	Last date
1893	1893-04-07	1893-09-21
1894	1894-04-28	1894-10-16
1895	1895-03-29	1895-09-25
1896	1896-05-05	1896-09-02
1897	1897-04-22	1897-10-15
1898	1898-05-23	1898-09-29
1899	1899-05-16	1899-10-23
1900	1900-05-12	1900-10-05
1901	1901-04-28	1901-09-28
1902	1902-04-21	1902-08-31
1903	1903-05-17	1903-09-09
1904	1904-05-23	1904-09-29
1905	1905-06-05	1905-10-05
1906	1906-05-17	1906-10-05
1907	1907-03-22	1907-09-20
1908	1908-05-13	1908-09-27
1909	1909-05-30	1909-09-21
1910	1910-03-24	1910-10-17
1911	1911-05-10	1911-09-15
1912	1912-05-23	1912-10-07
1913	1913-05-29	1913-09-11
1914	1914-05-11	1914-09-21
1915	1915-04-25	1915-09-14
1916	1916-06-30	1916-10-09
1917	1917-05-18	1917-09-06
1918	1918-05-04	1918-10-15
1919	1919-05-30	1919-10-01
1920	1920-06-08	1920-10-11
1921	1921-05-20	1921-09-22
1922	1922-05-10	1922-10-05
1923	1923-06-01	1923-09-05
1924	1924-05-05	1924-08-30
1925	1925-04-22	1925-09-19
1926	1926-04-30	1926-09-21
1927	1927-05-21	1927-10-27
1928	1928-05-03	1928-10-11
1929	1929-05-28	1929-09-27
1930	1930-04-10	1930-10-10
1931	1931-05-16	1931-10-04
1932	1932-05-14	1932-09-19
1933	1933-06-01	1933-09-25
1934	1934-05-03	1934-09-25
1935	1935-06-12	1935-09-24
1936	1936-04-30	1936-09-22
1937	1937-05-29	1937-10-29
1938	1938-06-21	1938-10-14
1939	1939-05-23	1939-10-07
1940	1940-05-13	1940-10-26
1941	1941-05-15	1941-09-22
1942	1942-04-29	1942-09-17
1943	1943-05-29	1943-09-03
1944	1944-05-14	1944-09-17
1945	1945-06-23	1945-09-09
1946	1946-06-07	1946-09-27
1952	1952-04-29	1952-09-30
1953	1953-05-25	1953-10-19
1954	1954-06-09	1954-10-03
1955	1955-05-20	1955-09-18
1956	1956-05-12	1956-10-12
1957	1957-06-05	1957-09-01
1958	1958-05-11	1958-08-30
1959	1959-05-02	1959-09-22
1960	1960-06-28	1960-09-08
1961	1961-05-31	1961-09-11
1962	1962-05-05	1962-10-11
1963	1963-05-08	1963-10-15
1964	1964-05-18	1964-09-10
1965	1965-05-01	1965-09-10
1966	1966-05-26	1966-09-03
1967	1967-05-18	1967-08-17
1968	1968-05-02	1968-09-04
1969	1969-05-03	1969-10-04
1970	1970-04-28	1970-09-21
1971	1971-05-14	1971-10-01
1972	1972-05-18	1972-09-20
1973	1973-06-07	1973-09-02
1974	1974-06-14	1974-08-27
1975	1975-05-18	1975-10-14
1976	1976-05-20	1976-10-03
1977	1977-04-16	1977-09-08
1978	1978-05-25	1978-09-20
1979	1979-05-08	1979-09-28
1980	1980-04-21	1980-09-21
1981	1981-04-02	1981-10-01
1982	1982-06-28	1982-10-02
1983	1983-06-09	1983-10-02
1984	1984-05-18	1984-09-25
1985	1985-04-18	1985-09-20
1986	1986-03-29	1986-09-26
1987	1987-04-20	1987-09-06
1988	1988-05-14	1988-09-23
1989	1989-05-29	1989-08-28
1990	1990-06-12	1990-10-06
1991	1991-05-12	1991-09-15
1992	1992-05-16	1992-08-25
1993	1993-06-11	1993-09-13
1994	1994-04-18	1994-10-01
1995	1995-06-07	1995-09-14
1996	1996-05-17	1996-09-05
1997	1997-05-18	1997-10-06
1998	1998-05-14	1998-09-27
1999	1999-05-28	1999-09-07
2000	2000-06-01	2000-09-19
2001	2001-05-15	2001-09-07
2002	2002-04-15	2002-10-01
2003	2003-04-01	2003-09-11
2004	2004-04-16	2004-09-19
2005	2005-06-02	2005-10-05
2006	2006-04-13	2006-10-04
2007	2007-04-29	2007-10-08
2008	2008-06-01	2008-09-03
2009	2009-04-24	2009-08-16
2010	2010-04-01	2010-10-10
2011	2011-05-10	2011-10-09
2012	2012-05-03	2012-09-13
2013	2013-04-30	2013-10-03
2014	2014-05-08	2014-09-05
2015	2015-06-05	2015-09-18
2016	2016-05-07	2016-10-18
2017	2017-05-16	2017-10-04
2018	2018-05-25	2018-10-04
2019	2019-05-17	2019-10-02
2020	2020-05-26	2020-09-07
2021	2021-05-02	2021-10-01
2022	2022-05-10	2022-09-21
2023	2023-05-08	2023-10-04
2024	2024-04-15	2024-10-12
2025	2025-05-15	2025-10-05
2026	2026-03-22	2026-10-12

Every Fixed Threshold

Fixed thresholds at Iowa City
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	129	93	1901	52
35 C (95 F): Days	112	37	1988	4
40 C (104 F): Days	8	11	1934	6
90 F (32.2 C): Days	129	63	1988	26
100 F (37.8 C): Days	38	23	1936	2
0 C (32 F): Ice days (max	129	72	1978	30
0 C (32 F): Frost days (min	129	168	1952	83
-10 C (14 F): Days with min	129	73	1893	33
-20 C (-4 F): Days with min	128	38	1963	7
-30 C (-22 F): Days with min	26	8	1905	3
20 C (68 F): Tropical nights (min	129	52	1983	32
25 C (77 F): Days with min	33	6	1988	1
10 mm (0.39 in): Days with 10 mm or more rain	128	47	1993	35
25 mm (0.98 in): Days with 25 mm or more rain	128	19	1993	17
50 mm (1.97 in): Days with 50 mm or more rain	95	6	1978	3
100 mm (3.94 in): Days with 100 mm or more rain	16	2	1930	1
10 cm (3.9 in): Days with 10 cm or more snowfall	83	5	1959	3
25 cm (9.8 in): Days with 25 cm or more snowfall	6	1	1932	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1893.

Download the Data

Data for Iowa 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).

Iowa City Threshold Days by Year (USC00134101)

Key Facts for Iowa City Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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