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

Helena 1 S Threshold Days by Year (USC00013783)

5 fixed thresholds counted per year at Helena 1 S (USC00013783): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Helena 1 S Thresholds

  • Helena 1 S: days with 10 mm (0.39 in) or more of precipitation in 30 years, most in 1929 with 66.
  • Helena 1 S: days with 25 mm (0.98 in) or more of precipitation in 30 years, most in 1918 with 25.
  • Helena 1 S: days with 50 mm (1.97 in) or more of precipitation in 30 years, most in 1929 with 11.
  • Helena 1 S: days with 100 mm (3.94 in) or more of precipitation in 11 years, most in 1929 with 3.
  • 5 fixed thresholds have at least one qualifying day at Helena 1 S.
30 years with a qualifying day
Days with 10 mm (0.39 in) or more of precipitation per year at Helena 1 S Days per year at Helena 1 S with 10 mm (0.39 in) or more of precipitation, with the decade average as a line. The most was 66 in 1929. 0204060801917: 501918: 451919: 531920: 521921: 431922: 521923: 481924: 411925: 341926: 501927: 421928: 421929: 661930: 411931: 341932: 551933: 331934: 421935: 391936: 501937: 491938: 451939: 491940: 451941: 371942: 351943: 361944: 451949: 451950: 551917192019231926192919321935193819411944
Days per year at Helena 1 S with 10 mm (0.39 in) or more of precipitation, with the decade average as a line. The most was 66 in 1929.
Days with 10 mm (0.39 in) or more of precipitation per year at Helena 1 S
YearDaysDecade average
19175049.3
19184549.3
19195349.3
19205247
19214347
19225247
19234847
19244147
19253447
19265047
19274247
19284247
19296647
19304143.7
19313443.7
19325543.7
19333343.7
19344243.7
19353943.7
19365043.7
19374943.7
19384543.7
19394943.7
19404540.5
19413740.5
19423540.5
19433640.5
19444540.5
19494540.5
19505555
First to last qualifying date each year at Helena 1 S For each year, a bar from the first to the last day at Helena 1 S meeting 10 mm (0.39 in). 1917: 31 January 1917 to 12 December 19171918: 6 January 1918 to 24 December 19181919: 2 January 1919 to 19 December 19191920: 7 January 1920 to 27 December 19201921: 9 January 1921 to 25 December 19211922: 5 January 1922 to 31 December 19221923: 1 January 1923 to 23 December 19231924: 2 January 1924 to 31 December 19241925: 9 January 1925 to 20 December 19251926: 3 January 1926 to 28 December 19261927: 14 January 1927 to 31 December 19271928: 9 January 1928 to 18 December 19281929: 6 January 1929 to 22 December 19291930: 3 January 1930 to 26 December 19301931: 5 January 1931 to 31 December 19311932: 6 January 1932 to 31 December 19321933: 9 January 1933 to 19 December 19331934: 1 January 1934 to 28 December 19341935: 1 January 1935 to 29 December 19351936: 2 January 1936 to 31 December 19361937: 2 January 1937 to 28 December 19371938: 1 January 1938 to 27 December 19381939: 5 January 1939 to 27 December 19391940: 7 January 1940 to 27 December 19401941: 15 January 1941 to 26 December 19411942: 4 January 1942 to 28 December 19421943: 8 January 1943 to 29 December 19431944: 3 January 1944 to 11 December 19441949: 5 January 1949 to 23 December 19491950: 6 January 1950 to 29 December 195019171921192519291933193719411949JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day at Helena 1 S meeting 10 mm (0.39 in).
First to last qualifying date each year at Helena 1 S
YearFirst dateLast date
19171917-01-311917-12-12
19181918-01-061918-12-24
19191919-01-021919-12-19
19201920-01-071920-12-27
19211921-01-091921-12-25
19221922-01-051922-12-31
19231923-01-011923-12-23
19241924-01-021924-12-31
19251925-01-091925-12-20
19261926-01-031926-12-28
19271927-01-141927-12-31
19281928-01-091928-12-18
19291929-01-061929-12-22
19301930-01-031930-12-26
19311931-01-051931-12-31
19321932-01-061932-12-31
19331933-01-091933-12-19
19341934-01-011934-12-28
19351935-01-011935-12-29
19361936-01-021936-12-31
19371937-01-021937-12-28
19381938-01-011938-12-27
19391939-01-051939-12-27
19401940-01-071940-12-27
19411941-01-151941-12-26
19421942-01-041942-12-28
19431943-01-081943-12-29
19441944-01-031944-12-11
19491949-01-051949-12-23
19501950-01-061950-12-29

Every Fixed Threshold

Fixed thresholds at Helena 1 S
ThresholdYears with a qualifying dayMost days in a yearYearLatest year days
10 mm (0.39 in): Days with 10 mm or more rain3066192955
25 mm (0.98 in): Days with 25 mm or more rain3025191818
50 mm (1.97 in): Days with 50 mm or more rain301119295
100 mm (3.94 in): Days with 100 mm or more rain11319291
200 mm (7.87 in): Days with 200 mm or more rain1119421

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1917.

Download the Data

  • Data for Helena 1 S 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).