Harper Threshold Days by Year (USC00353666)

17 fixed thresholds counted per year at Harper (USC00353666): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Harper Thresholds

Harper: days with 10 mm (0.39 in) or more of precipitation in 41 years, most in 1956 with 9.
Harper: days with a maximum temperature at or above 30 C (86 F) in 39 years, most in 1967 with 100.
Harper: days with a maximum temperature at or above 35 C (95 F) in 39 years, most in 1929 with 47.
Harper: days with a maximum temperature at or above 90 F (32.2 C) in 39 years, most in 1967 with 80.
17 fixed thresholds have at least one qualifying day at Harper.

Days at or above 30 C (86 F)

39 years with a qualifying day

Days per year at Harper with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 100 in 1967.

Days at or above 30 C (86 F) per year at Harper
Year	Days	Decade average
1920	68	75
1921	76	75
1922	84	75
1923	65	75
1926	72	75
1927	67	75
1928	84	75
1929	84	75
1930	80	72.7
1931	92	72.7
1932	69	72.7
1933	74	72.7
1934	86	72.7
1935	64	72.7
1936	63	72.7
1937	68	72.7
1938	65	72.7
1939	66	72.7
1940	73	55.5
1941	43	55.5
1942	58	55.5
1943	48	55.5
1955	79	71.4
1956	76	71.4
1957	76	71.4
1958	79	71.4
1959	47	71.4
1961	66	73.6
1962	73	73.6
1963	74	73.6
1964	59	73.6
1965	50	73.6
1966	88	73.6
1967	100	73.6
1968	67	73.6
1969	85	73.6
1971	67	69.3
1973	67	69.3
1974	74	69.3

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

First to last qualifying date each year at Harper
Year	First date	Last date
1920	1920-06-19	1920-10-05
1921	1921-06-06	1921-09-01
1922	1922-05-16	1922-10-10
1923	1923-05-08	1923-09-14
1926	1926-04-28	1926-08-29
1927	1927-04-25	1927-09-22
1928	1928-05-05	1928-09-25
1929	1929-05-12	1929-09-17
1930	1930-05-27	1930-09-19
1931	1931-05-05	1931-10-02
1932	1932-05-12	1932-09-30
1933	1933-05-25	1933-09-17
1934	1934-04-12	1934-09-18
1935	1935-05-21	1935-09-11
1936	1936-04-17	1936-09-22
1937	1937-05-03	1937-09-17
1938	1938-05-24	1938-09-23
1939	1939-04-28	1939-09-24
1940	1940-05-10	1940-09-07
1941	1941-05-11	1941-08-17
1942	1942-04-21	1942-09-13
1943	1943-06-17	1943-09-15
1955	1955-05-20	1955-09-13
1956	1956-05-18	1956-09-27
1957	1957-05-30	1957-09-28
1958	1958-05-18	1958-09-11
1959	1959-06-12	1959-09-12
1961	1961-05-24	1961-09-06
1962	1962-04-23	1962-09-25
1963	1963-05-21	1963-10-03
1964	1964-05-16	1964-09-24
1965	1965-05-29	1965-09-03
1966	1966-05-03	1966-09-28
1967	1967-05-17	1967-09-29
1968	1968-05-28	1968-09-12
1969	1969-05-07	1969-09-28
1971	1971-05-01	1971-09-12
1973	1973-05-14	1973-09-13
1974	1974-05-27	1974-09-24

Every Fixed Threshold

Fixed thresholds at Harper
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	39	100	1967	74
35 C (95 F): Days	39	47	1929	21
40 C (104 F): Days	11	3	1920	2
90 F (32.2 C): Days	39	80	1967	52
100 F (37.8 C): Days	33	23	1971	3
110 F (43.3 C): Days	1	1	1961	1
0 C (32 F): Ice days (max	39	41	1930	15
0 C (32 F): Frost days (min	39	199	1922	173
-10 C (14 F): Days with min	39	77	1929	25
-20 C (-4 F): Days with min	27	22	1929	9
-30 C (-22 F): Days with min	8	4	1930	3
20 C (68 F): Tropical nights (min	15	5	1971	1
10 mm (0.39 in): Days with 10 mm or more rain	41	9	1956	5
25 mm (0.98 in): Days with 25 mm or more rain	9	2	1940	1
50 mm (1.97 in): Days with 50 mm or more rain	1	0	n/a	1
10 cm (3.9 in): Days with 10 cm or more snowfall	22	2	1922	1
25 cm (9.8 in): Days with 25 cm or more snowfall	1	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 1920.

Download the Data

Data for Harper 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).

Harper Threshold Days by Year (USC00353666)

Key Facts for Harper Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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