Arrowrock Dam Threshold Days by Year (USC00100448)

18 fixed thresholds counted per year at Arrowrock Dam (USC00100448): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Arrowrock Dam Thresholds

Arrowrock Dam: days with 10 mm (0.39 in) or more of precipitation in 90 years, most in 1983 with 28.
Arrowrock Dam: nights with a minimum temperature at or below 0 C (32 F) in 78 years, most in 1977 with 171.
Arrowrock Dam: nights with a minimum temperature at or below -10 C (14 F) in 77 years, most in 1930 with 51.
Arrowrock Dam: days with a maximum temperature at or above 30 C (86 F) in 76 years, most in 1934 with 91.
18 fixed thresholds have at least one qualifying day at Arrowrock Dam.

Days at or above 30 C (86 F)

76 years with a qualifying day

Days per year at Arrowrock Dam with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 91 in 1934.

Days at or above 30 C (86 F) per year at Arrowrock Dam
Year	Days	Decade average
1912	68	71.8
1913	74	71.8
1914	82	71.8
1918	56	71.8
1919	79	71.8
1920	61	68.4
1921	62	68.4
1922	77	68.4
1923	65	68.4
1924	85	68.4
1925	62	68.4
1926	71	68.4
1928	64	68.4
1930	75	71.1
1931	88	71.1
1932	60	71.1
1933	73	71.1
1934	91	71.1
1935	63	71.1
1936	65	71.1
1937	49	71.1
1938	72	71.1
1939	75	71.1
1940	90	64.6
1941	61	64.6
1942	62	64.6
1943	64	64.6
1944	50	64.6
1945	61	64.6
1946	64	64.6
1947	64	64.6
1948	60	64.6
1949	70	64.6
1950	60	65.1
1951	52	65.1
1952	65	65.1
1953	59	65.1
1954	58	65.1
1955	68	65.1
1956	67	65.1
1957	71	65.1
1958	78	65.1
1959	73	65.1
1960	78	63.3
1961	85	63.3
1962	58	63.3
1963	62	63.3
1964	48	63.3
1965	37	63.3
1966	78	63.3
1967	81	63.3
1968	49	63.3
1969	57	63.3
1970	66	56
1971	57	56
1972	58	56
1973	63	56
1974	60	56
1975	52	56
1976	33	56
1977	63	56
1978	40	56
1979	68	56
1980	40	56
1981	70	56
1982	53	56
1983	51	56
1984	59	56
1989	63	56
1990	73	65.8
1991	66	65.8
1992	71	65.8
1993	32	65.8
1994	90	65.8
1999	63	65.8
2003	88	88

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

First to last qualifying date each year at Arrowrock Dam
Year	First date	Last date
1912	1912-05-17	1912-09-30
1913	1913-05-06	1913-09-28
1914	1914-05-07	1914-10-16
1918	1918-06-05	1918-09-29
1919	1919-05-15	1919-09-17
1920	1920-06-20	1920-10-05
1921	1921-06-11	1921-09-02
1922	1922-06-03	1922-10-11
1923	1923-05-09	1923-09-15
1924	1924-05-03	1924-09-30
1925	1925-06-18	1925-09-26
1926	1926-04-30	1926-09-10
1928	1928-05-07	1928-09-18
1930	1930-05-28	1930-09-23
1931	1931-05-07	1931-09-18
1932	1932-05-13	1932-10-01
1933	1933-05-30	1933-09-20
1934	1934-04-22	1934-10-01
1935	1935-05-23	1935-10-03
1936	1936-05-12	1936-09-22
1937	1937-05-14	1937-09-19
1938	1938-05-26	1938-09-24
1939	1939-04-29	1939-09-25
1940	1940-05-10	1940-09-27
1941	1941-05-12	1941-09-18
1942	1942-05-22	1942-10-10
1943	1943-06-18	1943-10-03
1944	1944-05-15	1944-09-13
1945	1945-06-20	1945-09-15
1946	1946-04-26	1946-09-30
1947	1947-05-03	1947-09-25
1948	1948-05-25	1948-09-22
1949	1949-05-13	1949-09-28
1950	1950-06-05	1950-09-08
1951	1951-06-15	1951-09-20
1952	1952-05-25	1952-09-27
1953	1953-06-12	1953-09-22
1954	1954-05-16	1954-09-22
1955	1955-06-08	1955-09-14
1956	1956-05-23	1956-09-26
1957	1957-06-02	1957-10-01
1958	1958-05-11	1958-09-11
1959	1959-05-12	1959-09-12
1960	1960-05-10	1960-09-27
1961	1961-05-22	1961-09-15
1962	1962-06-18	1962-09-26
1963	1963-06-13	1963-10-03
1964	1964-05-17	1964-08-26
1965	1965-06-10	1965-10-03
1966	1966-05-03	1966-09-25
1967	1967-05-18	1967-09-30
1968	1968-06-03	1968-09-14
1969	1969-05-24	1969-09-28
1970	1970-05-17	1970-10-04
1971	1971-06-21	1971-09-11
1972	1972-05-30	1972-09-05
1973	1973-05-16	1973-09-14
1974	1974-06-12	1974-09-07
1975	1975-05-15	1975-10-03
1976	1976-05-14	1976-09-11
1977	1977-04-25	1977-09-11
1978	1978-06-09	1978-09-27
1979	1979-05-23	1979-10-07
1980	1980-05-22	1980-09-07
1981	1981-06-23	1981-09-19
1982	1982-06-12	1982-09-10
1983	1983-05-25	1983-09-08
1984	1984-05-30	1984-09-20
1989	1989-05-07	1989-09-30
1990	1990-06-09	1990-10-01
1991	1991-06-10	1991-09-26
1992	1992-04-29	1992-10-02
1993	1993-05-12	1993-09-11
1994	1994-04-19	1994-09-29
1999	1999-05-20	1999-09-24
2003	2003-05-24	2003-10-06

Every Fixed Threshold

Fixed thresholds at Arrowrock Dam
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	76	91	1934	88
35 C (95 F): Days	76	49	1931	33
40 C (104 F): Days	35	12	1931	2
90 F (32.2 C): Days	76	77	1940	52
100 F (37.8 C): Days	72	25	1931	14
110 F (43.3 C): Days	2	2	1931	2
0 C (32 F): Ice days (max	76	52	1930	4
0 C (32 F): Frost days (min	78	171	1977	94
-10 C (14 F): Days with min	77	51	1930	6
-20 C (-4 F): Days with min	42	26	1949	8
-30 C (-22 F): Days with min	3	3	1937	3
20 C (68 F): Tropical nights (min	35	7	2003	7
25 C (77 F): Days with min	1	1	1931	1
10 mm (0.39 in): Days with 10 mm or more rain	90	28	1983	13
25 mm (0.98 in): Days with 25 mm or more rain	70	6	1913	1
50 mm (1.97 in): Days with 50 mm or more rain	4	1	1953	1
10 cm (3.9 in): Days with 10 cm or more snowfall	63	9	1948	4
25 cm (9.8 in): Days with 25 cm or more snowfall	14	2	1949	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1912.

Download the Data

Data for Arrowrock Dam 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 2025-12-31. Last revised 31 December 2025 (2025-12-31).

Arrowrock Dam Threshold Days by Year (USC00100448)

Key Facts for Arrowrock Dam Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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