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Built 2026-10-19 (19 October 2026)

Half Moon Bay Threshold Days by Year (USC00043714)

8 fixed thresholds counted per year at Half Moon Bay (USC00043714): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Half Moon Bay Thresholds

  • Half Moon Bay: days with 10 mm (0.39 in) or more of precipitation in 79 years, most in 1983 with 41.
  • Half Moon Bay: days with 25 mm (0.98 in) or more of precipitation in 78 years, most in 1983 with 18.
  • Half Moon Bay: nights with a minimum temperature at or below 0 C (32 F) in 54 years, most in 2007 with 25.
  • Half Moon Bay: days with 50 mm (1.97 in) or more of precipitation in 43 years, most in 1982 with 6.
  • 8 fixed thresholds have at least one qualifying day at Half Moon Bay.
34 years with a qualifying day
Days at or above 30 C (86 F) per year at Half Moon Bay Days per year at Half Moon Bay with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 5 in 2019. 02461941: 11944: 11946: 41947: 11954: 21955: 11956: 11958: 31959: 21961: 21964: 11965: 41966: 41967: 21968: 11970: 21972: 11976: 11978: 21979: 21983: 21991: 11992: 11993: 21995: 11997: 22004: 32008: 12010: 12014: 12017: 42019: 52020: 22023: 1194119541959196619721983199520102020
Days per year at Half Moon Bay with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 5 in 2019.
Days at or above 30 C (86 F) per year at Half Moon Bay
YearDaysDecade average
194111.8
194411.8
194641.8
194711.8
195421.8
195511.8
195611.8
195831.8
195921.8
196122.3
196412.3
196542.3
196642.3
196722.3
196812.3
197021.6
197211.6
197611.6
197821.6
197921.6
198322
199111.4
199211.4
199321.4
199511.4
199721.4
200432
200812
201012.8
201412.8
201742.8
201952.8
202021.5
202311.5
First to last qualifying date each year at Half Moon Bay For each year, a bar from the first to the last day at Half Moon Bay meeting 30 C (86 F). 1941: 3 October 1941 to 3 October 19411944: 8 September 1944 to 8 September 19441946: 18 September 1946 to 11 October 19461947: 20 September 1947 to 20 September 19471954: 24 September 1954 to 14 October 19541955: 12 October 1955 to 12 October 19551956: 23 September 1956 to 23 September 19561958: 16 September 1958 to 28 September 19581959: 13 October 1959 to 24 October 19591961: 15 October 1961 to 16 October 19611964: 20 October 1964 to 20 October 19641965: 21 October 1965 to 24 October 19651966: 27 September 1966 to 1 November 19661967: 15 October 1967 to 16 October 19671968: 30 August 1968 to 30 August 19681970: 22 September 1970 to 26 September 19701972: 6 October 1972 to 6 October 19721976: 12 October 1976 to 12 October 19761978: 23 September 1978 to 24 September 19781979: 10 September 1979 to 11 September 19791983: 20 September 1983 to 26 October 19831991: 20 October 1991 to 20 October 19911992: 7 October 1992 to 7 October 19921993: 25 October 1993 to 26 October 19931995: 2 October 1995 to 2 October 19951997: 28 September 1997 to 15 October 19972004: 12 October 2004 to 14 October 20042008: 23 October 2008 to 23 October 20082010: 12 October 2010 to 12 October 20102014: 3 October 2014 to 3 October 20142017: 3 September 2017 to 25 October 20172019: 9 June 2019 to 25 October 20192020: 15 October 2020 to 16 October 20202023: 5 October 2023 to 5 October 20231941195519641970198319972017JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day at Half Moon Bay meeting 30 C (86 F).
First to last qualifying date each year at Half Moon Bay
YearFirst dateLast date
19411941-10-031941-10-03
19441944-09-081944-09-08
19461946-09-181946-10-11
19471947-09-201947-09-20
19541954-09-241954-10-14
19551955-10-121955-10-12
19561956-09-231956-09-23
19581958-09-161958-09-28
19591959-10-131959-10-24
19611961-10-151961-10-16
19641964-10-201964-10-20
19651965-10-211965-10-24
19661966-09-271966-11-01
19671967-10-151967-10-16
19681968-08-301968-08-30
19701970-09-221970-09-26
19721972-10-061972-10-06
19761976-10-121976-10-12
19781978-09-231978-09-24
19791979-09-101979-09-11
19831983-09-201983-10-26
19911991-10-201991-10-20
19921992-10-071992-10-07
19931993-10-251993-10-26
19951995-10-021995-10-02
19971997-09-281997-10-15
20042004-10-122004-10-14
20082008-10-232008-10-23
20102010-10-122010-10-12
20142014-10-032014-10-03
20172017-09-032017-10-25
20192019-06-092019-10-25
20202020-10-152020-10-16
20232023-10-052023-10-05

Every Fixed Threshold

Fixed thresholds at Half Moon Bay
ThresholdYears with a qualifying dayMost days in a yearYearLatest year days
30 C (86 F): Days34520191
90 F (32.2 C): Days15219581
0 C (32 F): Frost days (min542520072
20 C (68 F): Tropical nights (min1119831
10 mm (0.39 in): Days with 10 mm or more rain7941198312
25 mm (0.98 in): Days with 25 mm or more rain781819836
50 mm (1.97 in): Days with 50 mm or more rain43619821
100 mm (3.94 in): Days with 100 mm or more rain4119621

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1941.

Download the Data

  • Data for Half Moon Bay 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 . Last revised (2026-10-17).