Brunswick, Maine climate: Normal weather by month, frost dates and records
Brunswick's normal year runs from 12°F January nights to 79°F July afternoons, with 50.0 inches of precipitation and 67 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.6°C, January lows of −11°C, July highs of 26°C, 1,270 mm of precipitation a year.
- NOAA stationBrunswick Naval Air Station
- Station IDUSW00014611
- Location43.90°N 69.93°W
- Elevation70 ft (21 m)
- From the center1 miles
- Population (town)22,631
- Census place16,928
On October 22, the normal high in Brunswick is 56°F and the normal low 37°F, and the chance of measurable rain or snow is 35%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Brunswick.
- Jan 30° 12°
- Feb 33° 14°
- Mar 41° 24°
- Apr 53° 32°
- May 64° 44°
- Jun 73° 53°
- Jul 79° 59°
- Aug 78° 58°
- Sep 70° 50°
- Oct 58° 39°
- Nov 47° 30°
- Dec 37° 20°
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 Brunswick each month?
July is the warmest month, with normal highs of 79°F; January the coldest, with normal lows of 12°F. The most precipitation falls in October (6.00 in), the least in August (3.27 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 30°F | 12°F | 21.0°F | 3.46 | 19.3 | 11 | <1 | 30 | 9 h 10 min |
| February | 33°F | 14°F | 23.2°F | 3.50 | 13.6 | 10 | <1 | 26 | 10 h 30 min |
| March | 41°F | 24°F | 32.2°F | 4.06 | 18.7 | 12 | <1 | 25 | 11 h 50 min |
| April | 53°F | 32°F | 42.6°F | 4.28 | 3.3 | 10 | <1 | 15 | 13 h 20 min |
| May | 64°F | 44°F | 53.9°F | 4.06 | 0.0 | 13 | <1 | 1 | 14 h 40 min |
| June | 73°F | 53°F | 63.1°F | 4.21 | 0.0 | 11 | 1 | <1 | 15 h 30 min |
| July | 79°F | 59°F | 69.3°F | 3.48 | 0.0 | 11 | 2 | <1 | 15 h 10 min |
| August | 78°F | 58°F | 68.0°F | 3.27 | 0.0 | 8 | 1 | <1 | 14 h |
| September | 70°F | 50°F | 60.3°F | 4.20 | 0.0 | 9 | <1 | <1 | 12 h 40 min |
| October | 58°F | 39°F | 48.5°F | 6.00 | 0.2 | 11 | <1 | 8 | 11 h 10 min |
| November | 47°F | 30°F | 38.1°F | 5.19 | 1.9 | 12 | <1 | 19 | 9 h 40 min |
| December | 37°F | 20°F | 28.3°F | 4.30 | 9.8 | 11 | <1 | 28 | 9 h |
| Year (annual) | 55°F | 36°F | 45.7°F | 50.01 | 66.8 | 128 | 4 | 151 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −11°C | −6.1°C | 88 mm | 49 cm |
| February | 0°C | −10°C | −4.9°C | 89 mm | 35 cm |
| March | 5°C | −5°C | 0.1°C | 103 mm | 47 cm |
| April | 12°C | 0°C | 5.9°C | 109 mm | 8 cm |
| May | 18°C | 7°C | 12.2°C | 103 mm | 0 cm |
| June | 23°C | 12°C | 17.3°C | 107 mm | 0 cm |
| July | 26°C | 15°C | 20.7°C | 88 mm | 0 cm |
| August | 26°C | 15°C | 20.0°C | 83 mm | 0 cm |
| September | 21°C | 10°C | 15.7°C | 107 mm | 0 cm |
| October | 14°C | 4°C | 9.2°C | 152 mm | 1 cm |
| November | 8°C | −1°C | 3.4°C | 132 mm | 5 cm |
| December | 3°C | −7°C | −2.1°C | 109 mm | 25 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014611; 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 Brunswick?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, August has the fewest days with rain (8).
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 USW00014611.
When is the last frost in Brunswick?
In Brunswick, the last spring frost (32°F) comes after May 2 in half of years and after May 14 in one year in ten; the first autumn frost comes before October 10 in half of years and before September 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
- May 21 year in 10 after May 14; 9 in 10 after April 24
- First autumn frost, half of years before
- October 101 year in 10 before September 29; 9 in 10 before October 27
NOAA puts the median frost-free season at 160 days, and the season without a hard freeze (28°F) at 183 days.
A hard freeze (28°F) comes after April 22 in half of springs and before October 23 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Brunswick in zone 5b in ZIP code 04011. By the map's own method, the average of each year's coldest night over 1991-2020, Brunswick's NOAA station is in zone 5b: the coldest night of a typical year reaches −11°F (16 complete years).
Frost dates for every NOAA station in Maine · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00014611; 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.
How hot and how cold does it get in Brunswick?
In a normal year in Brunswick, 4 days a year reach 90°F, 151 nights fall to 32°F or colder and 128 days bring measurable precipitation.
- Days at 90°F or more
- 4a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 151a normal year
- Days that stay below freezing
- 46high of 32°F or less
- Days with 0.01 inch of precipitation
- 128a normal year
- Days with 1 inch of snow or more
- 17a normal year
The highest temperature in this station's record (since 1945) is 104°F, on August 2, 1975; the lowest is −30°F, on January 4, 1981.
The wettest calendar year on that record is 1983, with 67.37 in; the snowiest season is 1970–71, with 148.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014611; records: ACIS (NOAA Regional Climate Centers), station USW00014611. Records use complete months only; a month missing more than three days is left out.
How sunny is Brunswick?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Brunswick, 3.8 kWh per square metre a day. August is the sunniest month (81%) and December the cloudiest (62%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 64% | 1.6 |
| February | 69% | 2.5 |
| March | 70% | 3.7 |
| April | 70% | 4.8 |
| May | 70% | 5.5 |
| June | 72% | 5.8 |
| July | 79% | 6.0 |
| August | 81% | 5.5 |
| September | 80% | 4.4 |
| October | 71% | 2.8 |
| November | 67% | 1.8 |
| December | 62% | 1.3 |
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 Brunswick need?
A normal year in Brunswick brings 7,341 heating degree days, 37% more than the median U.S. place (5,373), and 352 cooling degree days, 61% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,120 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,364 | 0 |
| February | 1,170 | 0 |
| March | 1,017 | 0 |
| April | 674 | 0 |
| May | 349 | 7 |
| June | 107 | 50 |
| July | 16 | 151 |
| August | 23 | 118 |
| September | 165 | 26 |
| October | 511 | 1 |
| November | 806 | 0 |
| December | 1,139 | 0 |
| Year (annual) | 7,341 | 352 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014611. 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.
How does Brunswick's climate compare?
Brunswick is warmer than 32 of the other 41 places with their own NOAA record in Maine, and wetter than 33. Across the 7,247 U.S. stations with normals, its annual mean of 45.7°F is warmer than 22%.
In the Köppen classification computed from these normals, Brunswick is Dfb: continental, no dry season, warm 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 Brunswick share this climate record?
Topsham has no NOAA station with 1991-2020 normals of its 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.
- Topsham, ME9,820 people · 3 mi N
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 Brunswick's climate
What is the coldest month in Brunswick?
January, with a normal high of 30°F and a normal low of 12°F. The warmest is July (79°F by day, 59°F at night).
Does it snow in Brunswick?
Yes: 67 inches in a normal year, falling on 29 days with 0.1 inch or more, the most in January (19.3 inches).
What is the rainiest month in Brunswick?
October, with 6.00 in of precipitation in a normal year; the driest is August with 3.27 in.
What plant hardiness zone is Brunswick in?
The USDA's 2023 map puts Brunswick in zone 5b in ZIP code 04011. By the same method at Brunswick's NOAA station, the coldest night of a typical year reaches −11°F (16 years, 1991-2020): zone 5b.
How late can frost come in Brunswick?
In half of years the last 32°F night comes after May 2; in one year in ten it comes after May 14. Waiting until May 14 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Maine climateThe statewide normals and every place in the state
- Bath, ME4 miles from this station, 44.6°F a year
- Durham, ME11 miles from this station, 43.9°F a year
- Westport Island, ME11 miles from this station, 46.0°F a year
- Wiscasset, ME12 miles from this station, 45.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made