Boston, Massachusetts climate: Normal weather by month, frost dates and records
Boston's normal year runs from 23°F January nights to 82°F July afternoons, with 43.6 inches of precipitation and 49 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.1°C, January lows of −5°C, July highs of 28°C, 1,107 mm of precipitation a year.
- NOAA stationBoston Logan International Airport
- Station IDUSW00014739
- Location42.36°N 71.01°W
- Elevation12 ft (4 m)
- From the center2 miles
- Population673,458
On October 8, the normal high in Boston is 65°F and the normal low 50°F, and the chance of measurable rain or snow is 33%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Boston.
- Jan 37° 23°
- Feb 39° 25°
- Mar 46° 31°
- Apr 56° 41°
- May 67° 50°
- Jun 76° 60°
- Jul 82° 66°
- Aug 80° 65°
- Sep 73° 58°
- Oct 62° 48°
- Nov 52° 38°
- Dec 42° 29°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Boston each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 23°F. The most precipitation falls in December (4.30 in), the least in February (3.21 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 37°F | 23°F | 29.9°F | 3.39 | 14.3 | 12 | <1 | 25 | 9 h 20 min |
| February | 39°F | 25°F | 31.8°F | 3.21 | 14.4 | 11 | <1 | 22 | 10 h 30 min |
| March | 46°F | 31°F | 38.3°F | 4.17 | 9.0 | 12 | <1 | 16 | 11 h 50 min |
| April | 56°F | 41°F | 48.6°F | 3.63 | 1.6 | 12 | <1 | 2 | 13 h 20 min |
| May | 67°F | 50°F | 58.4°F | 3.25 | 0.0 | 12 | 1 | <1 | 14 h 30 min |
| June | 76°F | 60°F | 68.0°F | 3.89 | 0.0 | 11 | 3 | <1 | 15 h 20 min |
| July | 82°F | 66°F | 74.1°F | 3.27 | 0.0 | 9 | 6 | <1 | 15 h |
| August | 80°F | 65°F | 72.7°F | 3.23 | 0.0 | 9 | 4 | <1 | 14 h |
| September | 73°F | 58°F | 65.6°F | 3.56 | 0.0 | 9 | 1 | <1 | 12 h 30 min |
| October | 62°F | 48°F | 54.8°F | 4.03 | 0.2 | 11 | <1 | <1 | 11 h 10 min |
| November | 52°F | 38°F | 44.7°F | 3.66 | 0.7 | 10 | <1 | 7 | 9 h 50 min |
| December | 42°F | 29°F | 35.7°F | 4.30 | 9.0 | 12 | <1 | 20 | 9 h 10 min |
| Year (annual) | 59°F | 45°F | 51.9°F | 43.59 | 49.2 | 128 | 14 | 92 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 3°C | −5°C | −1.2°C | 86 mm | 36 cm |
| February | 4°C | −4°C | −0.1°C | 82 mm | 37 cm |
| March | 8°C | 0°C | 3.5°C | 106 mm | 23 cm |
| April | 14°C | 5°C | 9.2°C | 92 mm | 4 cm |
| May | 19°C | 10°C | 14.7°C | 83 mm | 0 cm |
| June | 25°C | 15°C | 20.0°C | 99 mm | 0 cm |
| July | 28°C | 19°C | 23.4°C | 83 mm | 0 cm |
| August | 27°C | 18°C | 22.6°C | 82 mm | 0 cm |
| September | 23°C | 15°C | 18.7°C | 90 mm | 0 cm |
| October | 17°C | 9°C | 12.7°C | 102 mm | 1 cm |
| November | 11°C | 3°C | 7.1°C | 93 mm | 2 cm |
| December | 6°C | −2°C | 2.1°C | 109 mm | 23 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014739; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Boston?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August has the fewest days with rain (9).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014739.
When is the last frost in Boston?
In Boston, the last spring frost (32°F) comes after April 4 in half of years and after April 17 in one year in ten; the first autumn frost comes before November 9 in half of years and before October 29 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 41 year in 10 after April 17; 9 in 10 after March 25
- First autumn frost, half of years before
- November 91 year in 10 before October 29; 9 in 10 before November 22
NOAA puts the median frost-free season at 218 days, and the season without a hard freeze (28°F) at 239 days.
A hard freeze (28°F) comes after March 28 in half of springs and before November 21 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Boston in zones 6b to 7a across its 25 ZIP code areas (6b in 02132, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Boston's NOAA station is in zone 7a: the coldest night of a typical year reaches 3°F (30 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Massachusetts · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00014739; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Boston ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Boston's 25 ZIP code areas run from zone 6b to 7a: 11 in 6b and 14 in 7a. Each ZIP's frost dates are in the frost tool.
| ZIP code | Zone | Land in Boston |
|---|---|---|
| 02108 | 7a | 0.7 km² |
| 02111 | 7a | 0.5 km² |
| 02114 | 7a | 1.1 km² |
| 02115 | 7a | 1.8 km² |
| 02116 | 7a | 1.7 km² |
| 02118 | 7a | 2.8 km² |
| 02119 | 7a | 4.2 km² |
| 02120 | 7a | 1.6 km² |
| 02121 | 6b | 4.9 km² |
| 02122 | 7a | 4.4 km² |
| 02124 | 6b | 7.7 km² |
| 02125 | 7a | 5.6 km² |
| 02126 | 6b | 4.7 km² |
| 02127 | 7a | 5.3 km² |
| 02128 | 7a | 12.2 km² |
| 02129 | 7a | 3.5 km² |
| 02130 | 6b | 9.2 km² |
| 02131 | 6b | 7.2 km² |
| 02132 | 6b | 12.6 km² |
| 02134 | 6b | 3.2 km² |
| 02135 | 6b | 6.7 km² |
| 02136 | 6b | 11.9 km² |
| 02210 | 7a | 2.4 km² |
| 02215 | 6b | 2.2 km² |
| 02467 | 6b | 1.5 km² |
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Boston?
In a normal year in Boston, 14 days a year reach 90°F, 92 nights fall to 32°F or colder and 128 days bring measurable precipitation.
- Days at 90°F or more
- 14a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 92a normal year
- Days that stay below freezing
- 23high of 32°F or less
- Days with 0.01 inch of precipitation
- 128a normal year
- Days with 1 inch of snow or more
- 11a normal year
The highest temperature in Boston's official record (kept by the National Weather Service since 1872) is 104°F, on July 4, 1911; the lowest is −18°F, on February 9, 1934.
The wettest calendar year on that record is 1878, with 65.53 in; the snowiest season is 2014–15, with 110.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014739; records: ACIS (NOAA Regional Climate Centers), NWS threaded record BOSthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Boston, and how clear are its skies?
The summer (June-August) dew point averages 60°F. The muggiest month is July, with an average dew point of 62°F; the driest air comes in January (17°F). February is the windiest month (12.8 mph on average), and September has the most clear or nearly clear hours (43%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 17°F | 58% | 49% | 12.1 mph | 38% | 36% |
| February | 22°F | 59% | 51% | 12.8 mph | 34% | 41% |
| March | 30°F | 59% | 50% | 12.3 mph | 34% | 41% |
| April | 40°F | 61% | 51% | 11.4 mph | 33% | 40% |
| May | 51°F | 67% | 57% | 10.8 mph | 29% | 38% |
| June | 60°F | 65% | 54% | 10.2 mph | 31% | 26% |
| July | 62°F | 68% | 57% | 9.6 mph | 34% | 24% |
| August | 59°F | 68% | 56% | 10.0 mph | 42% | 22% |
| September | 51°F | 70% | 59% | 10.5 mph | 43% | 29% |
| October | 39°F | 65% | 55% | 11.4 mph | 36% | 35% |
| November | 30°F | 64% | 55% | 11.6 mph | 34% | 39% |
| December | 21°F | 62% | 53% | 12.3 mph | 35% | 39% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014739. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Boston?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Boston, 3.8 kWh per square metre a day. August is the sunniest month (78%) and December the cloudiest (66%). Among the 459 U.S. places of 50,000 or more, that ranks tied 385th (with 30 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 69% | 1.8 |
| February | 70% | 2.7 |
| March | 69% | 3.7 |
| April | 69% | 4.7 |
| May | 68% | 5.3 |
| June | 71% | 5.7 |
| July | 78% | 6.0 |
| August | 78% | 5.3 |
| September | 77% | 4.3 |
| October | 68% | 2.8 |
| November | 70% | 2.0 |
| December | 66% | 1.5 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Boston need?
A normal year in Boston brings 5,545 heating degree days, 3% more than the median U.S. place (5,373), and 802 cooling degree days, 12% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,050 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,086 | 0 |
| February | 930 | 0 |
| March | 828 | 1 |
| April | 496 | 4 |
| May | 234 | 29 |
| June | 50 | 138 |
| July | 4 | 284 |
| August | 5 | 245 |
| September | 71 | 91 |
| October | 326 | 9 |
| November | 608 | 0 |
| December | 908 | 0 |
| Year (annual) | 5,545 | 802 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014739. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Boston been warmer than normal lately?
2025 averaged 52.2°F, 0.3°F above the 1991-2020 normal of 51.9°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 54.4°F | +2.5°F | 52.33 | 21.7 |
| 2022 | 53.6°F | +1.7°F | 31.25 | 54.6 |
| 2023 | 54.0°F | +2.1°F | 49.76 | 11.6 |
| 2024 | 53.7°F | +1.8°F | 45.39 | 15.3 |
| 2025 | 52.2°F | +0.3°F | 37.14 | 26.7 |
Over 86 complete years from 1936 to 2025, the station's annual mean temperature rose at a fitted 4.0°F per century (+0.22°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00014739; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Boston's climate compare?
Boston is warmer than 32 of the other 34 places with their own NOAA record in Massachusetts, and wetter than 6. Across the 7,247 U.S. stations with normals, its annual mean of 51.9°F is warmer than 49%.
In the Köppen classification computed from these normals, Boston is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Boston share this climate record?
9 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Somerville, MAalso near: Jamaica Plain (6 mi, 51.2°F a year); Reading (9 mi, 50.6°F a year)82,149 people · 5 mi NW
- Malden, MAalso near: Reading (7 mi, 50.6°F a year); Jamaica Plain (9 mi, 51.2°F a year)66,693 people · 5 mi NW
- Revere, MAalso near: Marblehead (8 mi, 48.7°F a year); Reading (10 mi, 50.6°F a year)60,702 people · 4 mi N
- Medford, MAalso near: Reading (7 mi, 50.6°F a year); Jamaica Plain (8 mi, 51.2°F a year)59,898 people · 7 mi NW
- Everett, MAalso near: Jamaica Plain (8 mi, 51.2°F a year); Reading (9 mi, 50.6°F a year)51,825 people · 4 mi NW
- Chelsea, MA40,245 people · 3 mi NW
- Winthrop, MA18,739 people · 2 mi NE
- Hull, MA10,278 people · 7 mi E
- Nahant, MA3,338 people · 6 mi NE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Boston's climate
What is the coldest month in Boston?
January, with a normal high of 37°F and a normal low of 23°F. The warmest is July (82°F by day, 66°F at night).
Does it snow in Boston?
Yes: 49 inches in a normal year, falling on 23 days with 0.1 inch or more, the most in February (14.4 inches).
What is the rainiest month in Boston?
December, with 4.30 in of precipitation in a normal year; the driest is February with 3.21 in.
What plant hardiness zone is Boston in?
The USDA's 2023 map puts Boston in zones 6b to 7a across its 25 ZIP code areas (6b in 02132, the largest). By the same method at Boston's NOAA station, the coldest night of a typical year reaches 3°F (30 years, 1991-2020): zone 7a.
How late can frost come in Boston?
In half of years the last 32°F night comes after April 4; in one year in ten it comes after April 17. Waiting until April 17 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Boston in OctoberThis month day by day, its records and recent years
- Massachusetts climateThe statewide normals and every place in the state
- Jamaica Plain, MA7 miles from this station, 51.2°F a year
- Hingham, MA11 miles from this station, 51.3°F a year
- Blue Hill, MA12 miles from this station, 49.7°F a year
- Marblehead, MA12 miles from this station, 48.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made