Koolau Dam 833 Threshold Days by Year

5 fixed thresholds counted per year at Koolau Dam 833 (USC00514766): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Koolau Dam 833 Thresholds

Koolau Dam 833: days with 10 mm (0.39 in) or more of precipitation in 54 years, most in 1974 with 127.
Koolau Dam 833: days with 25 mm (0.98 in) or more of precipitation in 54 years, most in 1974 with 59.
Koolau Dam 833: days with 50 mm (1.97 in) or more of precipitation in 54 years, most in 1980 with 24.
Koolau Dam 833: days with 100 mm (3.94 in) or more of precipitation in 38 years, most in 1965 with 8.
5 fixed thresholds have at least one qualifying day at Koolau Dam 833.

Days with 10 mm (0.39 in) or more of precipitation

54 years with a qualifying day

Days per year at Koolau Dam 833 with 10 mm (0.39 in) or more of precipitation, with the decade average as a line. The most was 127 in 1974.

Days with 10 mm (0.39 in) or more of precipitation per year at Koolau Dam 833
Year	Days	Decade average
1919	63	63
1920	75	65
1922	66	65
1923	77	65
1925	62	65
1926	32	65
1927	90	65
1928	59	65
1929	59	65
1932	65	48
1933	43	48
1934	44	48
1935	43	48
1936	64	48
1937	35	48
1938	49	48
1939	41	48
1940	22	70
1941	41	70
1942	54	70
1944	41	70
1945	85	70
1946	101	70
1947	86	70
1948	116	70
1949	84	70
1950	95	83.1
1951	88	83.1
1952	104	83.1
1953	64	83.1
1954	103	83.1
1955	86	83.1
1956	60	83.1
1957	91	83.1
1958	80	83.1
1959	60	83.1
1960	98	84
1961	89	84
1962	72	84
1963	83	84
1964	90	84
1965	85	84
1966	69	84
1967	99	84
1968	71	84
1973	94	93.6
1974	127	93.6
1975	79	93.6
1976	92	93.6
1977	88	93.6
1978	90	93.6
1979	85	93.6
1980	117	102.5
1981	88	102.5

For each year, a bar from the first to the last day at Koolau Dam 833 meeting 10 mm (0.39 in).

First to last qualifying date each year at Koolau Dam 833
Year	First date	Last date
1919	1919-01-12	1919-12-30
1920	1920-01-01	1920-12-24
1922	1922-01-20	1922-12-06
1923	1923-01-03	1923-12-31
1925	1925-01-08	1925-12-19
1926	1926-01-22	1926-12-25
1927	1927-01-04	1927-12-28
1928	1928-01-12	1928-12-15
1929	1929-01-14	1929-12-29
1932	1932-01-19	1932-12-11
1933	1933-01-01	1933-12-23
1934	1934-01-18	1934-12-27
1935	1935-01-02	1935-12-13
1936	1936-01-13	1936-12-30
1937	1937-01-13	1937-11-24
1938	1938-01-08	1938-12-27
1939	1939-01-23	1939-11-29
1940	1940-01-06	1940-11-19
1941	1941-03-03	1941-12-11
1942	1942-02-13	1942-12-31
1944	1944-01-06	1944-12-28
1945	1945-02-05	1945-12-12
1946	1946-01-08	1946-12-31
1947	1947-01-17	1947-12-27
1948	1948-01-01	1948-12-31
1949	1949-01-06	1949-12-28
1950	1950-01-02	1950-12-31
1951	1951-01-01	1951-12-31
1952	1952-01-04	1952-12-20
1953	1953-01-07	1953-12-27
1954	1954-01-01	1954-12-31
1955	1955-01-13	1955-12-22
1956	1956-01-02	1956-12-16
1957	1957-01-08	1957-12-29
1958	1958-01-28	1958-12-30
1959	1959-01-08	1959-12-17
1960	1960-01-04	1960-12-31
1961	1961-01-01	1961-12-12
1962	1962-01-07	1962-12-25
1963	1963-01-07	1963-12-12
1964	1964-01-01	1964-12-27
1965	1965-01-05	1965-12-25
1966	1966-01-03	1966-12-31
1967	1967-01-01	1967-12-31
1968	1968-01-02	1968-12-25
1973	1973-01-05	1973-12-31
1974	1974-01-01	1974-12-27
1975	1975-01-03	1975-12-17
1976	1976-01-03	1976-12-07
1977	1977-02-15	1977-12-18
1978	1978-01-16	1978-12-20
1979	1979-01-09	1979-12-25
1980	1980-01-07	1980-12-25
1981	1981-01-17	1981-12-25

Every Fixed Threshold

Fixed thresholds at Koolau Dam 833
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
10 mm (0.39 in): Days with 10 mm or more rain	54	127	1974	88
25 mm (0.98 in): Days with 25 mm or more rain	54	59	1974	29
50 mm (1.97 in): Days with 50 mm or more rain	54	24	1980	9
100 mm (3.94 in): Days with 100 mm or more rain	38	8	1965	2
200 mm (7.87 in): Days with 200 mm or more rain	7	1	1935	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1919.

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Data for Koolau Dam 833 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 2026-10-15 (15 October 2026). Threshold counts are computed by this site.

Data as of 2025-12-31. Last revised 31 December 2025 (2025-12-31).

Koolau Dam 833 Threshold Days by Year

Key Facts for Koolau Dam 833 Thresholds

Days with 10 mm (0.39 in) or more of precipitation

Every Fixed Threshold

Download the Data

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