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Data as of 2025-12-31
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Built 2026-10-19 (19 October 2026)

Napa Threshold Days by Year (USC00046065)

12 fixed thresholds counted per year at Napa (USC00046065): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Napa Thresholds

  • Napa: days with 10 mm (0.39 in) or more of precipitation in 25 years, most in 1909 with 35.
  • Napa: days with 25 mm (0.98 in) or more of precipitation in 25 years, most in 1907 with 12.
  • Napa: days with 50 mm (1.97 in) or more of precipitation in 14 years, most in 1914 with 3.
  • Napa: days with a maximum temperature at or above 30 C (86 F) in 9 years, most in 1914 with 57.
  • 12 fixed thresholds have at least one qualifying day at Napa.
9 years with a qualifying day
Days at or above 30 C (86 F) per year at Napa Days per year at Napa with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 57 in 1914. 02040601904: 451905: 451906: 501907: 101908: 211909: 281910: 271912: 351914: 57190419051906190719081909191019121914
Days per year at Napa with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 57 in 1914.
Days at or above 30 C (86 F) per year at Napa
YearDaysDecade average
19044533.2
19054533.2
19065033.2
19071033.2
19082133.2
19092833.2
19102739.7
19123539.7
19145739.7
First to last qualifying date each year at Napa For each year, a bar from the first to the last day at Napa meeting 30 C (86 F). 1904: 8 April 1904 to 4 October 19041905: 7 March 1905 to 11 October 19051906: 19 April 1906 to 6 October 19061907: 18 April 1907 to 4 October 19071908: 10 April 1908 to 7 October 19081909: 30 April 1909 to 25 October 19091910: 20 April 1910 to 25 October 19101912: 30 May 1912 to 16 October 19121914: 15 March 1914 to 13 October 191419041906190819101914JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day at Napa meeting 30 C (86 F).
First to last qualifying date each year at Napa
YearFirst dateLast date
19041904-04-081904-10-04
19051905-03-071905-10-11
19061906-04-191906-10-06
19071907-04-181907-10-04
19081908-04-101908-10-07
19091909-04-301909-10-25
19101910-04-201910-10-25
19121912-05-301912-10-16
19141914-03-151914-10-13

Every Fixed Threshold

Fixed thresholds at Napa
ThresholdYears with a qualifying dayMost days in a yearYearLatest year days
30 C (86 F): Days957191457
35 C (95 F): Days91619065
40 C (104 F): Days5419051
90 F (32.2 C): Days930190623
100 F (37.8 C): Days6719053
110 F (43.3 C): Days2119051
0 C (32 F): Frost days (min838190534
20 C (68 F): Tropical nights (min1119101
10 mm (0.39 in): Days with 10 mm or more rain2535190920
25 mm (0.98 in): Days with 25 mm or more rain2512190710
50 mm (1.97 in): Days with 50 mm or more rain14319142
100 mm (3.94 in): Days with 100 mm or more rain2119621

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1904.

Download the Data

  • Data for Napa 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).