Daily records
Page built 2026-10-19
Data as of 2026-10-17
Search
Built 2026-10-19 (19 October 2026)

Days at or above 100 F (37.8 C) in Boston

Boston has had days with a maximum temperature at or above 100 F (37.8 C) in 16 years, most in 1944 with 2. Days per year, season span, streaks and every date.

Key Facts for Boston

  • Boston has had days with a maximum temperature at or above 100 F (37.8 C) in 16 years, 20 days in all.
  • The most in one year was 2 days in 1944.
  • In 2026, the latest year on file, there were 2 such days.
  • The earliest first date in a year was 24 June 2025.
  • The latest last date in a year was 2 September 1953.
  • The longest run inside a single year was 2 days in 1944.
  • 1 year with under 90 percent of days observed is left out of these rankings.

Days per Year

16 years, 20 days
Days at or above 100 F (37.8 C) per year in Boston Days per year in Boston with a maximum temperature at or above 100 F (37.8 C). The line is the decade average. The most was 2 in 1944. Grey bars are years with under 90 percent of days observed, left out of rankings. 011221944: 21948: 11949: 21952: 21953: 11955: 11975: 11977: 11995: 12002: 12010: 12011: 12021: 12022: 12025: 12026: 219442010
Days per year in Boston with a maximum temperature at or above 100 F (37.8 C). The line is the decade average. The most was 2 in 1944. Grey bars are years with under 90 percent of days observed, left out of rankings.
Days at or above 100 F (37.8 C) per year in Boston
YearDaysDecade average
194421.7
194811.7
194921.7
195221.3
195311.3
195511.3
197511
197711
199511
200211
201011
201111
202111.3
202211.3
202511.3
202621.3

Season Span

earliest 24 June, latest 2 September
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 F (37.8 C). Long bars mean a long season. 1944: 12 August 1944 to 13 August 19441948: 27 August 1948 to 27 August 19481949: 4 July 1949 to 10 August 19491952: 26 June 1952 to 23 July 19521953: 2 September 1953 to 2 September 19531955: 5 August 1955 to 5 August 19551975: 2 August 1975 to 2 August 19751977: 21 July 1977 to 21 July 19771995: 14 July 1995 to 14 July 19952002: 14 August 2002 to 14 August 20022010: 6 July 2010 to 6 July 20102011: 22 July 2011 to 22 July 20112021: 30 June 2021 to 30 June 20212022: 24 July 2022 to 24 July 20222025: 24 June 2025 to 24 June 20252026: 2 July 2026 to 3 July 202619441949195319751995201020212025JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day in Boston meeting 100 F (37.8 C). Long bars mean a long season.
First to last qualifying date each year in Boston
YearFirst dateLast date
19441944-08-121944-08-13
19481948-08-271948-08-27
19491949-07-041949-08-10
19521952-06-261952-07-23
19531953-09-021953-09-02
19551955-08-051955-08-05
19751975-08-021975-08-02
19771977-07-211977-07-21
19951995-07-141995-07-14
20022002-08-142002-08-14
20102010-07-062010-07-06
20112011-07-222011-07-22
20212021-06-302021-06-30
20222022-07-242022-07-24
20252025-06-242025-06-24
20262026-07-022026-07-03

Every Year

Days at or above 100 F (37.8 C) per year in Boston
YearDaysFirst dateLast dateLongest streak in yearCoverage
202622 July 20263 July 20262 daysIncomplete, not ranked
2025124 June 202524 June 20251 daysComplete
2022124 July 202224 July 20221 daysComplete
2021130 June 202130 June 20211 daysComplete
2011122 July 201122 July 20111 daysComplete
201016 July 20106 July 20101 daysComplete
2002114 August 200214 August 20021 daysComplete
1995114 July 199514 July 19951 daysComplete
1977121 July 197721 July 19771 daysComplete
197512 August 19752 August 19751 daysComplete
195515 August 19555 August 19551 daysComplete
195312 September 19532 September 19531 daysComplete
1952226 June 195223 July 19521 daysComplete
194924 July 194910 August 19491 daysComplete
1948127 August 194827 August 19481 daysComplete
1944212 August 194413 August 19442 daysComplete
Decade averages for Days at or above 100 F (37.8 C) in Boston
DecadeAverage days per yearYears counted
1940s1.73
1950s1.33
1970s1.02
1990s1.01
2000s1.01
2010s1.02
2020s1.03

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 at or above 100 F (37.8 C) 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).