September
September · June · August
85climate match
United States · 1991–2020
Best time to visit
Boston.
September leads for comfortable weather in Boston: typically 23°C by day, 14.6°C at night, with 90 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortSeptember
Typical high23°C
Typical low14.6°C
Rain in September90 mm
July
July · August · June
78climate match
May
May · October · September
82climate match
The weakest month is January, scoring 5 against September’s 85 — days reach only 2.9°C, 21° below the 24°C the score treats as ideal.
Month by month
The whole year,
without the guesswork.
The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.
Jan
52.9° / -4.8°
Feb
54.1° / -4°
Mar
57.7° / -0.4°
Apr
3413.7° / 4.9°
May
6419.3° / 10.2°
Jun
8324.7° / 15.5°
Jul
6928° / 19°
Aug
7427° / 18.5°
Sep
8523° / 14.6°
Oct
5116.9° / 8.7°
Nov
2311.1° / 3.4°
Dec
55.8° / -1.4°
| Month | Day | Night | Rain | Wet days | Sea | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|---|
| January | 2.9°C | -4.8°C | 86 mm | 8.8 | 4.9°C | 9 h 24 | 5 | Strong coverage |
| February | 4.1°C | -4°C | 82 mm | 8.2 | 3.3°C | 10 h 29 | 5 | Strong coverage |
| March | 7.7°C | -0.4°C | 106 mm | 8.9 | 3.5°C | 11 h 48 | 5 | Strong coverage |
| April | 13.7°C | 4.9°C | 92 mm | 9.1 | 5.8°C | 13 h 18 | 34 | Strong coverage |
| May | 19.3°C | 10.2°C | 83 mm | 9.3 | 10.1°C | 14 h 34 | 64 | Strong coverage |
| June | 24.7°C | 15.5°C | 99 mm | 8.8 | 14.7°C | 15 h 16 | 83 | Strong coverage |
| July | 28°C | 19°C | 83 mm | 7.5 | 18.2°C | 14 h 59 | 69 | Strong coverage |
| August | 27°C | 18.5°C | 80 mm | 7 | 18.8°C | 13 h 54 | 74 | Strong coverage |
| September | 23°C | 14.6°C | 90 mm | 7.1 | 17.0°C | 12 h 26 | 85 | Strong coverage |
| October | 16.9°C | 8.7°C | 102 mm | 7.8 | 13.5°C | 10 h 59 | 51 | Strong coverage |
| November | 11.1°C | 3.4°C | 93 mm | 8.3 | 10.2°C | 9 h 43 | 23 | Strong coverage |
| December | 5.8°C | -1.4°C | 109 mm | 9.4 | 7.5°C | 9 h 06 | 5 | Strong coverage |
What has changed
Boston runs +0.9°C
on the 1961–1990 baseline.
Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.
Jan
+1.3
Feb
+1.6
Mar
+0.8
Apr
+0.7
May
+0.5
Jun
0.0
Jul
+0.9
Aug
+0.9
Sep
+1.0
Oct
+0.9
Nov
+0.5
Dec
+1.8
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 23.3°C12 Jan 2020 | -24.4°C15 Jan 1957 | 64 mm21 Jan 1979 | 268 mm1979 · driest 16 mm in 1989 | 91 |
| February | 22.8°C24 Feb 2017 | -25.6°C15 Feb 1943 | 68 mm13 Feb 2008 | 202 mm2008 · driest 17 mm in 2024 | 91 |
| March | 31.7°C31 Mar 1998 | -17.2°C5 Mar 1948 | 89 mm18 Mar 1968 | 378 mm2010 · driest 14 mm in 2006 | 91 |
| April | 34.4°C18 Apr 1976 | -8.9°C7 Apr 1982 | 109 mm1 Apr 2004 | 243 mm2004 · driest 21 mm in 1999 | 91 |
| May | 35.6°C19 May 2026 | 1.1°C10 May 2020 | 114 mm16 May 1954 | 340 mm1954 · driest 6 mm in 1944 | 91 |
| June | 38.9°C24 Jun 2025 | 5.0°C1 Jun 1945 | 145 mm13 Jun 1998 | 335 mm1982 · driest 0 mm in 1999 | 91 |
| July | 39.4°C22 Jul 2011 | 10.0°C1 Jul 1988 | 85 mm13 Jul 1996 | 265 mm2023 · driest 13 mm in 1952 | 91 |
| August | 38.9°C2 Aug 1975 | 7.8°C25 Aug 1940 | 179 mm19 Aug 1955 | 434 mm1955 · driest 17 mm in 2007 | 90 |
| September | 37.8°C2 Sep 1953 | 2.8°C27 Sep 1947 | 143 mm11 Sep 1954 | 251 mm1999 · driest 9 mm in 1957 | 90 |
| October | 32.2°C12 Oct 1954 | -3.9°C27 Oct 1936 | 155 mm20 Oct 1996 | 271 mm1996 · driest 9 mm in 1946 | 90 |
| November | 28.3°C2 Nov 1950 | -11.1°C26 Nov 1938 | 84 mm23 Nov 1992 | 235 mm2018 · driest 16 mm in 1976 | 90 |
| December | 24.4°C7 Dec 1998 | -23.9°C20 Dec 1942 | 107 mm12 Dec 1992 | 248 mm1969 · driest 21 mm in 1989 | 90 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 25 | 3 | 7 |
| February | 0 | 0 | 22 | 3 | 6 |
| March | <1 | 0 | 16 | 3 | 4 |
| April | 1 | <1 | 2 | 3 | <1 |
| May | 6 | 2 | 0 | 3 | 0 |
| June | 15 | 5 | 0 | 3 | 0 |
| July | 23 | 11 | 0 | 3 | 0 |
| August | 21 | 8 | 0 | 3 | 0 |
| September | 10 | 2 | 0 | 3 | 0 |
| October | 2 | <1 | <1 | 3 | <1 |
| November | <1 | 0 | 7 | 3 | <1 |
| December | 0 | 0 | 20 | 4 | 4 |
The best month has moved. On the 1961–1990 numbers the strongest month here was June (scoring 91); on 2011–2025 it is September (91). Both are scored the same way, from the same station — only the climate underneath changed.
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | <1% | 29% | 11% | 34% | -0.6–5.4°C |
| February | <1% | 29% | 10% | 34% | 1.1–6.6°C |
| March | 3% | 29% | 11% | 36% | 5.1–10.1°C |
| April | 12% | 31% | 10% | 38% | 11.2–15.6°C |
| May | 37% | 30% | 9% | 36% | 17.4–21.6°C |
| June | 63% | 28% | 9% | 31% | 22.5–26.6°C |
| July | 75% | 24% | 8% | 21% | 26.1–29.3°C |
| August | 75% | 24% | 9% | 23% | 25.4–28.3°C |
| September | 57% | 23% | 8% | 21% | 21.3–24.4°C |
| October | 23% | 23% | 9% | 23% | 15.5–19.1°C |
| November | 4% | 28% | 11% | 31% | 9.1–13.4°C |
| December | <1% | 30% | 11% | 36% | 2.8–8.0°C |
A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.
The evidence behind this page
Nearby, measured,
and named.
- Place identity
- GeoNames 4930956
- NOAA station
- USW00014739 · BOSTON
- Station distance
- 4.1 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 30 usable years
- Daylight
- Calculated from latitude 42.36°, mid-month, sunrise to sunset including refraction. Not a station measurement.
- Sea temperature
- NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 15 km from the place centre. A sheltered bay can run warmer than the open sea it is measured from.
- Important limit
- Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.