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Built 2026-10-19 (19 October 2026)

Nights at or above 25 C (77 F) in Boston

Boston has had nights with a minimum temperature at or above 25 C (77 F) in 31 years, most in 2002 with 4. Days per year, season span, streaks and every date.

Key Facts for Boston

  • Boston has had nights with a minimum temperature at or above 25 C (77 F) in 31 years, 56 days in all.
  • The most in one year was 4 days in 2002.
  • In 2026, the latest year on file, there were 2 such days.
  • The earliest first date in a year was 8 June 2008.
  • The latest last date in a year was 1 September 2010.
  • The longest run inside a single year was 3 days in 1991.
  • 1 year with under 90 percent of days observed is left out of these rankings.

Days per Year

31 years, 56 days
Nights at or above 25 C (77 F) per year in Boston Days per year in Boston with a minimum temperature at or above 25 C (77 F). The line is the decade average. The most was 4 in 2002. Grey bars are years with under 90 percent of days observed, left out of rankings. 012341948: 11949: 21952: 11953: 11963: 11969: 11973: 11975: 21977: 11984: 21988: 21991: 31993: 21999: 12001: 22002: 42003: 12006: 22008: 12010: 22011: 22012: 12013: 42016: 12018: 32019: 22020: 12021: 22022: 32025: 22026: 21948198820112026
Days per year in Boston with a minimum temperature at or above 25 C (77 F). The line is the decade average. The most was 4 in 2002. Grey bars are years with under 90 percent of days observed, left out of rankings.
Nights at or above 25 C (77 F) per year in Boston
YearDaysDecade average
194811.5
194921.5
195211
195311
196311
196911
197311.3
197521.3
197711.3
198422
198822
199132
199322
199912
200122
200242
200312
200622
200812
201022.1
201122.1
201212.1
201342.1
201612.1
201832.1
201922.1
202012
202122
202232
202522
202622

Season Span

earliest 8 June, latest 1 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 25 C (77 F). Long bars mean a long season. 1948: 28 August 1948 to 28 August 19481949: 28 July 1949 to 10 August 19491952: 19 July 1952 to 19 July 19521953: 31 August 1953 to 31 August 19531963: 28 July 1963 to 28 July 19631969: 18 July 1969 to 18 July 19691973: 30 August 1973 to 30 August 19731975: 1 August 1975 to 2 August 19751977: 20 July 1977 to 20 July 19771984: 9 June 1984 to 10 June 19841988: 11 August 1988 to 12 August 19881991: 19 July 1991 to 21 July 19911993: 12 July 1993 to 27 August 19931999: 5 July 1999 to 5 July 19992001: 25 July 2001 to 9 August 20012002: 3 July 2002 to 17 August 20022003: 6 July 2003 to 6 July 20032006: 1 August 2006 to 2 August 20062008: 8 June 2008 to 8 June 20082010: 5 July 2010 to 1 September 20102011: 12 July 2011 to 22 July 20112012: 21 June 2012 to 21 June 20122013: 5 July 2013 to 20 July 20132016: 12 August 2016 to 12 August 20162018: 3 August 2018 to 29 August 20182019: 20 July 2019 to 21 July 20192020: 28 July 2020 to 28 July 20202021: 29 June 2021 to 14 August 20212022: 25 July 2022 to 8 August 20222025: 24 June 2025 to 25 June 20252026: 2 July 2026 to 3 July 202619481963197719932003201120182022JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day in Boston meeting 25 C (77 F). Long bars mean a long season.
First to last qualifying date each year in Boston
YearFirst dateLast date
19481948-08-281948-08-28
19491949-07-281949-08-10
19521952-07-191952-07-19
19531953-08-311953-08-31
19631963-07-281963-07-28
19691969-07-181969-07-18
19731973-08-301973-08-30
19751975-08-011975-08-02
19771977-07-201977-07-20
19841984-06-091984-06-10
19881988-08-111988-08-12
19911991-07-191991-07-21
19931993-07-121993-08-27
19991999-07-051999-07-05
20012001-07-252001-08-09
20022002-07-032002-08-17
20032003-07-062003-07-06
20062006-08-012006-08-02
20082008-06-082008-06-08
20102010-07-052010-09-01
20112011-07-122011-07-22
20122012-06-212012-06-21
20132013-07-052013-07-20
20162016-08-122016-08-12
20182018-08-032018-08-29
20192019-07-202019-07-21
20202020-07-282020-07-28
20212021-06-292021-08-14
20222022-07-252022-08-08
20252025-06-242025-06-25
20262026-07-022026-07-03

Every Year

Nights at or above 25 C (77 F) per year in Boston
YearDaysFirst dateLast dateLongest streak in yearCoverage
202622 July 20263 July 20262 daysIncomplete, not ranked
2025224 June 202525 June 20252 daysComplete
2022325 July 20228 August 20222 daysComplete
2021229 June 202114 August 20211 daysComplete
2020128 July 202028 July 20201 daysComplete
2019220 July 201921 July 20192 daysComplete
201833 August 201829 August 20181 daysComplete
2016112 August 201612 August 20161 daysComplete
201345 July 201320 July 20132 daysComplete
2012121 June 201221 June 20121 daysComplete
2011212 July 201122 July 20111 daysComplete
201025 July 20101 September 20101 daysComplete
200818 June 20088 June 20081 daysComplete
200621 August 20062 August 20062 daysComplete
200316 July 20036 July 20031 daysComplete
200243 July 200217 August 20022 daysComplete
2001225 July 20019 August 20011 daysComplete
199915 July 19995 July 19991 daysComplete
1993212 July 199327 August 19931 daysComplete
1991319 July 199121 July 19913 daysComplete
1988211 August 198812 August 19882 daysComplete
198429 June 198410 June 19842 daysComplete
1977120 July 197720 July 19771 daysComplete
197521 August 19752 August 19752 daysComplete
1973130 August 197330 August 19731 daysComplete
1969118 July 196918 July 19691 daysComplete
1963128 July 196328 July 19631 daysComplete
1953131 August 195331 August 19531 daysComplete
1952119 July 195219 July 19521 daysComplete
1949228 July 194910 August 19491 daysComplete
1948128 August 194828 August 19481 daysComplete
Decade averages for Nights at or above 25 C (77 F) in Boston
DecadeAverage days per yearYears counted
1940s1.52
1950s1.02
1960s1.02
1970s1.33
1980s2.02
1990s2.03
2000s2.05
2010s2.17
2020s2.04

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 Nights at or above 25 C (77 F) 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).