Days at or above 30 C (86 F) in Boston

Boston has had days with a maximum temperature at or above 30 C (86 F) in 91 years, most in 1983 with 52. Days per year, season span, streaks and every date.

Key Facts for Boston

Boston has had days with a maximum temperature at or above 30 C (86 F) in 91 years, 2,611 days in all.
The most in one year was 52 days in 1983.
In 2026, the latest year on file, there were 37 such days.
The earliest first date in a year was 29 March 1945.
The latest last date in a year was 17 October 1938.
The longest run inside a single year was 14 days in 1988.
1 year with under 90 percent of days observed is left out of these rankings.

Days per Year

91 years, 2,611 days

Days per year in Boston with a maximum temperature at or above 30 C (86 F). The line is the decade average. The most was 52 in 1983. Grey bars are years with under 90 percent of days observed, left out of rankings.

Days at or above 30 C (86 F) per year in Boston
Year	Days	Decade average
1936	16	23.5
1937	28	23.5
1938	25	23.5
1939	25	23.5
1940	11	28.7
1941	30	28.7
1942	26	28.7
1943	29	28.7
1944	37	28.7
1945	30	28.7
1946	24	28.7
1947	36	28.7
1948	28	28.7
1949	36	28.7
1950	22	30.2
1951	22	30.2
1952	40	30.2
1953	31	30.2
1954	19	30.2
1955	46	30.2
1956	32	30.2
1957	28	30.2
1958	22	30.2
1959	40	30.2
1960	25	24.8
1961	38	24.8
1962	17	24.8
1963	29	24.8
1964	16	24.8
1965	32	24.8
1966	33	24.8
1967	9	24.8
1968	22	24.8
1969	27	24.8
1970	31	30.5
1971	38	30.5
1972	21	30.5
1973	34	30.5
1974	20	30.5
1975	31	30.5
1976	37	30.5
1977	41	30.5
1978	25	30.5
1979	27	30.5
1980	37	27.3
1981	25	27.3
1982	15	27.3
1983	52	27.3
1984	34	27.3
1985	17	27.3
1986	21	27.3
1987	16	27.3
1988	37	27.3
1989	19	27.3
1990	28	29.7
1991	42	29.7
1992	15	29.7
1993	32	29.7
1994	44	29.7
1995	40	29.7
1996	15	29.7
1997	27	29.7
1998	24	29.7
1999	30	29.7
2000	15	25
2001	28	25
2002	40	25
2003	23	25
2004	15	25
2005	34	25
2006	23	25
2007	34	25
2008	19	25
2009	19	25
2010	45	32.6
2011	33	32.6
2012	28	32.6
2013	27	32.6
2014	18	32.6
2015	34	32.6
2016	39	32.6
2017	24	32.6
2018	40	32.6
2019	38	32.6
2020	35	32.7
2021	37	32.7
2022	38	32.7
2023	22	32.7
2024	31	32.7
2025	29	32.7
2026	37	32.7

Season Span

earliest 29 March, latest 17 October

For each year, a bar from the first to the last day in Boston meeting 30 C (86 F). Long bars mean a long season.

First to last qualifying date each year in Boston
Year	First date	Last date
1936	1936-05-18	1936-09-08
1937	1937-05-31	1937-09-04
1938	1938-04-28	1938-10-17
1939	1939-05-28	1939-10-10
1940	1940-06-03	1940-09-21
1941	1941-04-20	1941-09-23
1942	1942-04-30	1942-09-16
1943	1943-06-02	1943-08-24
1944	1944-05-27	1944-10-07
1945	1945-03-29	1945-09-29
1946	1946-05-25	1946-10-07
1947	1947-05-13	1947-10-17
1948	1948-06-24	1948-09-18
1949	1949-05-05	1949-10-10
1950	1950-06-08	1950-09-01
1951	1951-05-15	1951-09-13
1952	1952-06-09	1952-09-29
1953	1953-05-11	1953-09-07
1954	1954-06-01	1954-10-13
1955	1955-05-04	1955-09-19
1956	1956-05-31	1956-10-16
1957	1957-04-21	1957-09-16
1958	1958-06-30	1958-09-26
1959	1959-05-20	1959-09-24
1960	1960-06-16	1960-09-09
1961	1961-05-15	1961-09-26
1962	1962-04-27	1962-09-14
1963	1963-05-09	1963-10-07
1964	1964-05-08	1964-09-11
1965	1965-05-10	1965-09-23
1966	1966-05-27	1966-09-02
1967	1967-06-10	1967-08-18
1968	1968-06-06	1968-08-25
1969	1969-05-17	1969-09-01
1970	1970-05-10	1970-09-25
1971	1971-06-07	1971-10-02
1972	1972-05-29	1972-09-17
1973	1973-05-29	1973-09-04
1974	1974-05-17	1974-09-13
1975	1975-05-20	1975-08-27
1976	1976-04-18	1976-09-14
1977	1977-04-13	1977-09-02
1978	1978-05-29	1978-09-21
1979	1979-05-09	1979-08-30
1980	1980-05-22	1980-09-22
1981	1981-05-25	1981-09-14
1982	1982-07-07	1982-09-10
1983	1983-06-11	1983-09-20
1984	1984-05-26	1984-08-30
1985	1985-05-11	1985-09-21
1986	1986-05-19	1986-09-30
1987	1987-05-30	1987-09-09
1988	1988-06-12	1988-08-28
1989	1989-06-22	1989-09-10
1990	1990-04-27	1990-10-06
1991	1991-04-07	1991-09-17
1992	1992-05-22	1992-08-27
1993	1993-05-11	1993-09-15
1994	1994-04-27	1994-09-17
1995	1995-05-24	1995-09-14
1996	1996-05-20	1996-08-23
1997	1997-06-10	1997-08-17
1998	1998-03-31	1998-09-27
1999	1999-05-31	1999-09-03
2000	2000-05-07	2000-09-01
2001	2001-05-02	2001-09-13
2002	2002-04-17	2002-09-10
2003	2003-06-25	2003-08-27
2004	2004-04-19	2004-08-30
2005	2005-04-20	2005-09-14
2006	2006-06-01	2006-08-14
2007	2007-04-23	2007-10-04
2008	2008-06-03	2008-09-05
2009	2009-04-26	2009-08-26
2010	2010-04-07	2010-09-25
2011	2011-05-27	2011-10-09
2012	2012-04-16	2012-08-31
2013	2013-05-30	2013-09-12
2014	2014-06-18	2014-09-28
2015	2015-05-10	2015-09-17
2016	2016-05-25	2016-09-14
2017	2017-04-16	2017-09-27
2018	2018-05-02	2018-10-10
2019	2019-05-20	2019-09-23
2020	2020-06-04	2020-08-25
2021	2021-05-22	2021-09-15
2022	2022-05-14	2022-08-31
2023	2023-04-13	2023-09-08
2024	2024-05-22	2024-08-28
2025	2025-06-05	2025-09-06
2026	2026-05-17	2026-10-02

Every Year

Days at or above 30 C (86 F) per year in Boston
Year	Days	First date	Last date	Longest streak in year	Coverage
2026	37	17 May 2026	2 October 2026	6 days	Incomplete, not ranked
2025	29	5 June 2025	6 September 2025	4 days	Complete
2024	31	22 May 2024	28 August 2024	7 days	Complete
2023	22	13 April 2023	8 September 2023	7 days	Complete
2022	38	14 May 2022	31 August 2022	7 days	Complete
2021	37	22 May 2021	15 September 2021	5 days	Complete
2020	35	4 June 2020	25 August 2020	5 days	Complete
2019	38	20 May 2019	23 September 2019	5 days	Complete
2018	40	2 May 2018	10 October 2018	6 days	Complete
2017	24	16 April 2017	27 September 2017	3 days	Complete
2016	39	25 May 2016	14 September 2016	8 days	Complete
2015	34	10 May 2015	17 September 2015	9 days	Complete
2014	18	18 June 2014	28 September 2014	5 days	Complete
2013	27	30 May 2013	12 September 2013	7 days	Complete
2012	28	16 April 2012	31 August 2012	7 days	Complete
2011	33	27 May 2011	9 October 2011	7 days	Complete
2010	45	7 April 2010	25 September 2010	5 days	Complete
2009	19	26 April 2009	26 August 2009	5 days	Complete
2008	19	3 June 2008	5 September 2008	5 days	Complete
2007	34	23 April 2007	4 October 2007	4 days	Complete
2006	23	1 June 2006	14 August 2006	5 days	Complete
2005	34	20 April 2005	14 September 2005	3 days	Complete
2004	15	19 April 2004	30 August 2004	3 days	Complete
2003	23	25 June 2003	27 August 2003	4 days	Complete
2002	40	17 April 2002	10 September 2002	9 days	Complete
2001	28	2 May 2001	13 September 2001	5 days	Complete
2000	15	7 May 2000	1 September 2000	3 days	Complete
1999	30	31 May 1999	3 September 1999	5 days	Complete
1998	24	31 March 1998	27 September 1998	6 days	Complete
1997	27	10 June 1997	17 August 1997	4 days	Complete
1996	15	20 May 1996	23 August 1996	3 days	Complete
1995	40	24 May 1995	14 September 1995	5 days	Complete
1994	44	27 April 1994	17 September 1994	13 days	Complete
1993	32	11 May 1993	15 September 1993	6 days	Complete
1992	15	22 May 1992	27 August 1992	2 days	Complete
1991	42	7 April 1991	17 September 1991	7 days	Complete
1990	28	27 April 1990	6 October 1990	6 days	Complete
1989	19	22 June 1989	10 September 1989	4 days	Complete
1988	37	12 June 1988	28 August 1988	14 days	Complete
1987	16	30 May 1987	9 September 1987	4 days	Complete
1986	21	19 May 1986	30 September 1986	4 days	Complete
1985	17	11 May 1985	21 September 1985	2 days	Complete
1984	34	26 May 1984	30 August 1984	5 days	Complete
1983	52	11 June 1983	20 September 1983	7 days	Complete
1982	15	7 July 1982	10 September 1982	4 days	Complete
1981	25	25 May 1981	14 September 1981	8 days	Complete
1980	37	22 May 1980	22 September 1980	6 days	Complete
1979	27	9 May 1979	30 August 1979	6 days	Complete
1978	25	29 May 1978	21 September 1978	5 days	Complete
1977	41	13 April 1977	2 September 1977	9 days	Complete
1976	37	18 April 1976	14 September 1976	6 days	Complete
1975	31	20 May 1975	27 August 1975	5 days	Complete
1974	20	17 May 1974	13 September 1974	4 days	Complete
1973	34	29 May 1973	4 September 1973	6 days	Complete
1972	21	29 May 1972	17 September 1972	4 days	Complete
1971	38	7 June 1971	2 October 1971	5 days	Complete
1970	31	10 May 1970	25 September 1970	5 days	Complete
1969	27	17 May 1969	1 September 1969	6 days	Complete
1968	22	6 June 1968	25 August 1968	5 days	Complete
1967	9	10 June 1967	18 August 1967	2 days	Complete
1966	33	27 May 1966	2 September 1966	4 days	Complete
1965	32	10 May 1965	23 September 1965	5 days	Complete
1964	16	8 May 1964	11 September 1964	5 days	Complete
1963	29	9 May 1963	7 October 1963	8 days	Complete
1962	17	27 April 1962	14 September 1962	2 days	Complete
1961	38	15 May 1961	26 September 1961	6 days	Complete
1960	25	16 June 1960	9 September 1960	4 days	Complete
1959	40	20 May 1959	24 September 1959	4 days	Complete
1958	22	30 June 1958	26 September 1958	3 days	Complete
1957	28	21 April 1957	16 September 1957	4 days	Complete
1956	32	31 May 1956	16 October 1956	5 days	Complete
1955	46	4 May 1955	19 September 1955	7 days	Complete
1954	19	1 June 1954	13 October 1954	3 days	Complete
1953	31	11 May 1953	7 September 1953	6 days	Complete
1952	40	9 June 1952	29 September 1952	7 days	Complete
1951	22	15 May 1951	13 September 1951	2 days	Complete
1950	22	8 June 1950	1 September 1950	5 days	Complete
1949	36	5 May 1949	10 October 1949	5 days	Complete
1948	28	24 June 1948	18 September 1948	6 days	Complete
1947	36	13 May 1947	17 October 1947	6 days	Complete
1946	24	25 May 1946	7 October 1946	6 days	Complete
1945	30	29 March 1945	29 September 1945	3 days	Complete
1944	37	27 May 1944	7 October 1944	8 days	Complete
1943	29	2 June 1943	24 August 1943	5 days	Complete
1942	26	30 April 1942	16 September 1942	4 days	Complete
1941	30	20 April 1941	23 September 1941	4 days	Complete
1940	11	3 June 1940	21 September 1940	3 days	Complete
1939	25	28 May 1939	10 October 1939	7 days	Complete
1938	25	28 April 1938	17 October 1938	4 days	Complete
1937	28	31 May 1937	4 September 1937	6 days	Complete
1936	16	18 May 1936	8 September 1936	3 days	Complete

Decade averages for Days at or above 30 C (86 F) in Boston
Decade	Average days per year	Years counted
1930s	23.5	4
1940s	28.7	10
1950s	30.2	10
1960s	24.8	10
1970s	30.5	10
1980s	27.3	10
1990s	29.7	10
2000s	25.0	10
2010s	32.6	10
2020s	32.0	6

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 30 C (86 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 2026-10-17. Last revised 17 October 2026 (2026-10-17).