Portland Downs Threshold Days by Year

4 fixed thresholds counted per year at Portland Downs (ASN00036039): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Portland Downs Thresholds

Portland Downs: days with 10 mm (0.39 in) or more of precipitation in 59 years, most in 1950 with 33.
Portland Downs: days with 25 mm (0.98 in) or more of precipitation in 58 years, most in 1950 with 16.
Portland Downs: days with 50 mm (1.97 in) or more of precipitation in 42 years, most in 1955 with 6.
Portland Downs: days with 100 mm (3.94 in) or more of precipitation in 8 years, most in 1955 with 2.
4 fixed thresholds have at least one qualifying day at Portland Downs.

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

59 years with a qualifying day

Days per year at Portland Downs with 10 mm (0.39 in) or more of precipitation, with the decade average as a line. The most was 33 in 1950.

Days with 10 mm (0.39 in) or more of precipitation per year at Portland Downs
Year	Days	Decade average
1888	6	6
1913	18	15.6
1914	13	15.6
1915	8	15.6
1916	22	15.6
1917	24	15.6
1918	15	15.6
1919	9	15.6
1920	19	12.7
1921	22	12.7
1922	9	12.7
1923	10	12.7
1924	21	12.7
1925	9	12.7
1926	8	12.7
1927	6	12.7
1928	13	12.7
1929	10	12.7
1930	13	10.9
1931	15	10.9
1932	8	10.9
1933	15	10.9
1934	8	10.9
1935	5	10.9
1936	15	10.9
1937	8	10.9
1938	11	10.9
1940	9	11
1941	24	11
1942	7	11
1943	4	11
1944	9	11
1945	10	11
1946	6	11
1947	13	11
1948	6	11
1949	22	11
1950	33	15.4
1951	8	15.4
1952	7	15.4
1953	9	15.4
1954	19	15.4
1955	22	15.4
1956	25	15.4
1957	8	15.4
1958	11	15.4
1959	12	15.4
1960	16	10.9
1961	10	10.9
1962	15	10.9
1963	16	10.9
1964	9	10.9
1965	8	10.9
1966	13	10.9
1967	9	10.9
1968	7	10.9
1969	6	10.9
1971	12	11.5
1972	11	11.5

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

First to last qualifying date each year at Portland Downs
Year	First date	Last date
1888	1888-01-23	1888-11-18
1913	1913-01-04	1913-12-22
1914	1914-01-20	1914-12-27
1915	1915-05-14	1915-12-27
1916	1916-01-14	1916-12-31
1917	1917-01-01	1917-12-24
1918	1918-01-02	1918-08-03
1919	1919-01-30	1919-12-21
1920	1920-02-07	1920-12-05
1921	1921-01-04	1921-12-27
1922	1922-01-31	1922-12-25
1923	1923-02-13	1923-12-25
1924	1924-01-06	1924-12-16
1925	1925-01-20	1925-11-19
1926	1926-01-27	1926-12-19
1927	1927-03-01	1927-12-23
1928	1928-02-18	1928-12-23
1929	1929-02-17	1929-12-10
1930	1930-01-24	1930-10-10
1931	1931-02-03	1931-12-06
1932	1932-02-08	1932-11-03
1933	1933-01-26	1933-12-25
1934	1934-01-28	1934-10-16
1935	1935-06-28	1935-12-30
1936	1936-01-06	1936-07-03
1937	1937-01-21	1937-11-19
1938	1938-01-09	1938-11-16
1940	1940-02-02	1940-08-21
1941	1941-01-02	1941-12-02
1942	1942-05-26	1942-12-08
1943	1943-02-05	1943-09-05
1944	1944-01-20	1944-12-19
1945	1945-01-17	1945-12-08
1946	1946-01-11	1946-11-18
1947	1947-01-30	1947-12-15
1948	1948-01-02	1948-12-06
1949	1949-01-09	1949-12-20
1950	1950-02-14	1950-12-19
1951	1951-01-01	1951-12-28
1952	1952-04-07	1952-12-15
1953	1953-01-16	1953-08-28
1954	1954-01-02	1954-10-16
1955	1955-01-15	1955-10-22
1956	1956-01-07	1956-12-22
1957	1957-01-10	1957-12-31
1958	1958-01-03	1958-12-29
1959	1959-01-26	1959-12-18
1960	1960-01-07	1960-12-30
1961	1961-01-02	1961-12-15
1962	1962-01-03	1962-12-30
1963	1963-01-11	1963-11-15
1964	1964-02-09	1964-12-27
1965	1965-03-09	1965-12-19
1966	1966-01-05	1966-12-05
1967	1967-01-18	1967-12-30
1968	1968-02-11	1968-05-13
1969	1969-02-08	1969-12-23
1971	1971-02-07	1971-12-26
1972	1972-01-05	1972-12-31

Every Fixed Threshold

Fixed thresholds at Portland Downs
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	59	33	1950	11
25 mm (0.98 in): Days with 25 mm or more rain	58	16	1950	3
50 mm (1.97 in): Days with 50 mm or more rain	42	6	1955	1
100 mm (3.94 in): Days with 100 mm or more rain	8	2	1955	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1888.

Download the Data

Data for Portland Downs 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 2026-10-14 (14 October 2026). Threshold counts are computed by this site.

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

Portland Downs Threshold Days by Year

Key Facts for Portland Downs Thresholds

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

Every Fixed Threshold

Download the Data

Related