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Built 2026-10-19 (19 October 2026)

Days with 100 mm (3.94 in) or more of precipitation in Boston

Boston has had days with 100 mm (3.94 in) or more of precipitation in 9 years, most in 1954 with 2. Days per year, season span, streaks and every date.

Key Facts for Boston

  • Boston has had days with 100 mm (3.94 in) or more of precipitation in 9 years, 11 days in all.
  • The most in one year was 2 days in 1954.
  • In 2004, the latest year on file, there were 1 such days.
  • The earliest first date in a year was 1 April 2004.
  • The latest last date in a year was 12 December 1992.
  • The longest run inside a single year was 2 days in 1955.
  • 1 year with under 90 percent of days observed is left out of these rankings.

Days per Year

9 years, 11 days
Days with 100 mm (3.94 in) or more of precipitation per year in Boston Days per year in Boston with 100 mm (3.94 in) or more of precipitation. The line is the decade average. The most was 2 in 1954. Grey bars are years with under 90 percent of days observed, left out of rankings. 011221954: 21955: 21984: 11992: 11996: 11998: 11999: 12000: 12004: 11954
Days per year in Boston with 100 mm (3.94 in) or more of precipitation. The line is the decade average. The most was 2 in 1954. Grey bars are years with under 90 percent of days observed, left out of rankings.
Days with 100 mm (3.94 in) or more of precipitation per year in Boston
YearDaysDecade average
195422
195522
198411
199211
199611
199811
199911
200011
200411

Season Span

earliest 1 April, latest 12 December
First to last qualifying date each year in Boston For each year, a bar from the first to the last day in Boston meeting 100 mm (3.94 in). Long bars mean a long season. 1954: 16 May 1954 to 11 September 19541955: 18 August 1955 to 19 August 19551984: 31 May 1984 to 31 May 19841992: 12 December 1992 to 12 December 19921996: 20 October 1996 to 20 October 19961998: 13 June 1998 to 13 June 19981999: 10 September 1999 to 10 September 19992000: 6 June 2000 to 6 June 20002004: 1 April 2004 to 1 April 200419541984199619992004JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day in Boston meeting 100 mm (3.94 in). Long bars mean a long season.
First to last qualifying date each year in Boston
YearFirst dateLast date
19541954-05-161954-09-11
19551955-08-181955-08-19
19841984-05-311984-05-31
19921992-12-121992-12-12
19961996-10-201996-10-20
19981998-06-131998-06-13
19991999-09-101999-09-10
20002000-06-062000-06-06
20042004-04-012004-04-01

Every Year

Days with 100 mm (3.94 in) or more of precipitation per year in Boston
YearDaysFirst dateLast dateLongest streak in yearCoverage
200411 April 20041 April 20041 daysComplete
200016 June 20006 June 20001 daysComplete
1999110 September 199910 September 19991 daysComplete
1998113 June 199813 June 19981 daysComplete
1996120 October 199620 October 19961 daysComplete
1992112 December 199212 December 19921 daysComplete
1984131 May 198431 May 19841 daysComplete
1955218 August 195519 August 19552 daysComplete
1954216 May 195411 September 19541 daysComplete
Decade averages for Days with 100 mm (3.94 in) or more of precipitation in Boston
DecadeAverage days per yearYears counted
1950s2.02
1980s1.01
1990s1.04
2000s1.02

Compare with your own threshold in the threshold explorer. Fahrenheit thresholds are converted to tenths of a degree Celsius once, rounding half up.

Download the Data

  • Data for Days with 100 mm (3.94 in) or more of precipitation in Boston, 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 from the threaded city record.

Data as of . Last revised (2026-10-17).