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

Portsmouth Threshold Days by Year (USC00376453)

11 fixed thresholds counted per year at Portsmouth (USC00376453): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Portsmouth Thresholds

  • Portsmouth: nights with a minimum temperature at or below 0 C (32 F) in 11 years, most in 1904 with 155.
  • Portsmouth: nights with a minimum temperature at or below -10 C (14 F) in 11 years, most in 1904 with 45.
  • Portsmouth: days with a maximum temperature at or above 30 C (86 F) in 10 years, most in 1944 with 20.
  • Portsmouth: days with a maximum temperature at or above 90 F (32.2 C) in 10 years, most in 1903 with 7.
  • 11 fixed thresholds have at least one qualifying day at Portsmouth.
10 years with a qualifying day
Days at or above 30 C (86 F) per year at Portsmouth Days per year at Portsmouth with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 20 in 1944. 051015201903: 161904: 71938: 91939: 151940: 71941: 121942: 151943: 121944: 201945: 91903190419381939194019411942194319441945
Days per year at Portsmouth with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 20 in 1944.
Days at or above 30 C (86 F) per year at Portsmouth
YearDaysDecade average
19031611.5
1904711.5
1938912
19391512
1940712.5
19411212.5
19421512.5
19431212.5
19442012.5
1945912.5
First to last qualifying date each year at Portsmouth For each year, a bar from the first to the last day at Portsmouth meeting 30 C (86 F). 1903: 18 May 1903 to 14 September 19031904: 26 June 1904 to 4 September 19041938: 30 July 1938 to 23 August 19381939: 7 May 1939 to 24 August 19391940: 9 July 1940 to 31 July 19401941: 2 August 1941 to 6 October 19411942: 30 April 1942 to 3 September 19421943: 3 June 1943 to 2 August 19431944: 31 May 1944 to 3 September 19441945: 15 June 1945 to 8 September 194519031938194019421944JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day at Portsmouth meeting 30 C (86 F).
First to last qualifying date each year at Portsmouth
YearFirst dateLast date
19031903-05-181903-09-14
19041904-06-261904-09-04
19381938-07-301938-08-23
19391939-05-071939-08-24
19401940-07-091940-07-31
19411941-08-021941-10-06
19421942-04-301942-09-03
19431943-06-031943-08-02
19441944-05-311944-09-03
19451945-06-151945-09-08

Every Fixed Threshold

Fixed thresholds at Portsmouth
ThresholdYears with a qualifying dayMost days in a yearYearLatest year days
30 C (86 F): Days102019449
35 C (95 F): Days3119031
90 F (32.2 C): Days10719032
0 C (32 F): Ice days (max1052190434
0 C (32 F): Frost days (min111551904108
-10 C (14 F): Days with min1145190430
-20 C (-4 F): Days with min4219041
20 C (68 F): Tropical nights (min81419381
10 mm (0.39 in): Days with 10 mm or more rain846190331
25 mm (0.98 in): Days with 25 mm or more rain81419409
50 mm (1.97 in): Days with 50 mm or more rain6319403

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1903.

Download the Data

  • Data for Portsmouth 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).