Grand River Dam Threshold Days by Year (USC00343700)

18 fixed thresholds counted per year at Grand River Dam (USC00343700): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Grand River Dam Thresholds

Grand River Dam: days with 10 mm (0.39 in) or more of precipitation in 36 years, most in 1973 with 53.
Grand River Dam: days with 25 mm (0.98 in) or more of precipitation in 36 years, most in 1943 with 17.
Grand River Dam: days with 50 mm (1.97 in) or more of precipitation in 34 years, most in 1959 with 6.
Grand River Dam: days with a maximum temperature at or above 30 C (86 F) in 32 years, most in 1956 with 129.
18 fixed thresholds have at least one qualifying day at Grand River Dam.

Days at or above 30 C (86 F)

32 years with a qualifying day

Days per year at Grand River Dam with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 129 in 1956.

Days at or above 30 C (86 F) per year at Grand River Dam
Year	Days	Decade average
1942	90	94.5
1943	96	94.5
1944	100	94.5
1945	94	94.5
1946	98	94.5
1947	103	94.5
1948	85	94.5
1949	90	94.5
1950	60	104
1951	88	104
1952	111	104
1953	124	104
1954	127	104
1955	116	104
1956	129	104
1957	78	104
1958	106	104
1959	101	104
1960	97	93
1961	69	93
1962	109	93
1964	96	93
1965	98	93
1968	83	93
1969	99	93
1970	102	101
1971	102	101
1972	114	101
1973	91	101
1975	104	101
1976	77	101
1978	117	101

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

First to last qualifying date each year at Grand River Dam
Year	First date	Last date
1942	1942-04-07	1942-09-18
1943	1943-04-10	1943-09-22
1944	1944-05-13	1944-11-04
1945	1945-05-13	1945-09-23
1946	1946-03-31	1946-10-07
1947	1947-04-29	1947-10-20
1948	1948-04-07	1948-09-23
1949	1949-04-07	1949-10-20
1950	1950-05-03	1950-10-31
1951	1951-04-27	1951-10-05
1952	1952-04-30	1952-10-14
1953	1953-05-20	1953-10-03
1954	1954-04-03	1954-10-17
1955	1955-03-10	1955-10-06
1956	1956-05-05	1956-10-12
1957	1957-05-15	1957-10-02
1958	1958-04-23	1958-10-17
1959	1959-04-30	1959-09-28
1960	1960-04-06	1960-10-10
1961	1961-04-24	1961-09-24
1962	1962-04-29	1962-10-15
1964	1964-04-24	1964-10-17
1965	1965-04-21	1965-10-10
1968	1968-05-02	1968-10-30
1969	1969-05-26	1969-10-04
1970	1970-04-27	1970-10-03
1971	1971-05-06	1971-10-01
1972	1972-04-11	1972-10-12
1973	1973-05-10	1973-10-03
1975	1975-04-24	1975-10-12
1976	1976-06-01	1976-10-02
1978	1978-04-09	1978-10-22

Every Fixed Threshold

Fixed thresholds at Grand River Dam
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	32	129	1956	117
35 C (95 F): Days	32	89	1954	55
40 C (104 F): Days	15	26	1954	5
45 C (113 F): Days	1	2	1954	2
90 F (32.2 C): Days	32	114	1954	88
100 F (37.8 C): Days	28	58	1954	26
110 F (43.3 C): Days	2	8	1954	1
0 C (32 F): Ice days (max	31	22	1948	20
0 C (32 F): Frost days (min	31	103	1960	92
-10 C (14 F): Days with min	31	17	1960	12
-20 C (-4 F): Days with min	7	1	1943	1
20 C (68 F): Tropical nights (min	31	93	1954	26
25 C (77 F): Days with min	25	22	1954	1
10 mm (0.39 in): Days with 10 mm or more rain	36	53	1973	26
25 mm (0.98 in): Days with 25 mm or more rain	36	17	1943	14
50 mm (1.97 in): Days with 50 mm or more rain	34	6	1959	5
100 mm (3.94 in): Days with 100 mm or more rain	13	2	1943	1
10 cm (3.9 in): Days with 10 cm or more snowfall	16	5	1958	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1942.

Download the Data

Data for Grand River 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).

Grand River Dam Threshold Days by Year (USC00343700)

Key Facts for Grand River Dam Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

Related