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Data as of 2025-12-31
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Built 2026-10-18 (18 October 2026)

Altamont Threshold Days by Year

4 fixed thresholds counted per year at Altamont (USC00400116): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Altamont Thresholds

  • Altamont: days with 10 mm (0.39 in) or more of precipitation in 14 years, most in 1950 with 66.
  • Altamont: days with 25 mm (0.98 in) or more of precipitation in 14 years, most in 1957 with 27.
  • Altamont: days with 50 mm (1.97 in) or more of precipitation in 13 years, most in 1957 with 11.
  • Altamont: days with 100 mm (3.94 in) or more of precipitation in 5 years, most in 1954 with 1.
  • 4 fixed thresholds have at least one qualifying day at Altamont.
14 years with a qualifying day
Days with 10 mm (0.39 in) or more of precipitation per year at Altamont Days per year at Altamont with 10 mm (0.39 in) or more of precipitation, with the decade average as a line. The most was 66 in 1950. 0204060801930: 251949: 521950: 661951: 491952: 471953: 421954: 451955: 551956: 411957: 611958: 391959: 471960: 431961: 481930195019521954195619581960
Days per year at Altamont with 10 mm (0.39 in) or more of precipitation, with the decade average as a line. The most was 66 in 1950.
Days with 10 mm (0.39 in) or more of precipitation per year at Altamont
YearDaysDecade average
19302525
19495252
19506649.2
19514949.2
19524749.2
19534249.2
19544549.2
19555549.2
19564149.2
19576149.2
19583949.2
19594749.2
19604345.5
19614845.5
First to last qualifying date each year at Altamont For each year, a bar from the first to the last day at Altamont meeting 10 mm (0.39 in). 1930: 10 January 1930 to 18 November 19301949: 4 January 1949 to 23 December 19491950: 3 January 1950 to 29 December 19501951: 4 January 1951 to 26 December 19511952: 5 January 1952 to 31 December 19521953: 3 January 1953 to 29 December 19531954: 3 January 1954 to 30 December 19541955: 6 January 1955 to 18 December 19551956: 19 January 1956 to 23 December 19561957: 5 January 1957 to 26 December 19571958: 14 January 1958 to 28 December 19581959: 16 January 1959 to 28 December 19591960: 3 January 1960 to 30 December 19601961: 1 January 1961 to 18 December 19611930195019521954195619581960JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day at Altamont meeting 10 mm (0.39 in).
First to last qualifying date each year at Altamont
YearFirst dateLast date
19301930-01-101930-11-18
19491949-01-041949-12-23
19501950-01-031950-12-29
19511951-01-041951-12-26
19521952-01-051952-12-31
19531953-01-031953-12-29
19541954-01-031954-12-30
19551955-01-061955-12-18
19561956-01-191956-12-23
19571957-01-051957-12-26
19581958-01-141958-12-28
19591959-01-161959-12-28
19601960-01-031960-12-30
19611961-01-011961-12-18

Every Fixed Threshold

Fixed thresholds at Altamont
ThresholdYears with a qualifying dayMost days in a yearYearLatest year days
10 mm (0.39 in): Days with 10 mm or more rain1466195048
25 mm (0.98 in): Days with 25 mm or more rain1427195724
50 mm (1.97 in): Days with 50 mm or more rain131119574
100 mm (3.94 in): Days with 100 mm or more rain5119541

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1930.

Download the Data

  • Data for Altamont 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 (2025-12-31).