Plymouth, New Hampshire climate: Normal weather by month, frost dates and records
Plymouth's normal year runs from 7°F January nights to 80°F July afternoons, with 44.5 inches of precipitation and 68 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.3°C, January lows of −14°C, July highs of 27°C, 1,129 mm of precipitation a year.
- NOAA stationPlymouth
- Station IDUSC00276945
- Location43.78°N 71.65°W
- Elevation660 ft (201 m)
- From the center4 miles
- Population (town)6,621
- Census place4,877
On October 23, the normal high in Plymouth is 55°F and the normal low 31°F, and the chance of measurable rain or snow is 40%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Plymouth.
- Jan 29° 7°
- Feb 33° 8°
- Mar 41° 18°
- Apr 55° 29°
- May 67° 39°
- Jun 75° 49°
- Jul 80° 54°
- Aug 79° 52°
- Sep 72° 45°
- Oct 58° 34°
- Nov 46° 25°
- Dec 34° 15°
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 Plymouth each month?
July is the warmest month, with normal highs of 80°F; January the coldest, with normal lows of 7°F. The most precipitation falls in October (4.56 in), the least in February (2.62 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 29°F | 7°F | 18.1°F | 3.20 | 18.0 | 13 | <1 | 31 | 9 h 20 min |
| February | 33°F | 8°F | 20.6°F | 2.62 | 15.7 | 9 | <1 | 28 | 10 h 30 min |
| March | 41°F | 18°F | 29.5°F | 3.15 | 13.5 | 11 | <1 | 30 | 11 h 50 min |
| April | 55°F | 29°F | 41.7°F | 3.34 | 3.4 | 10 | <1 | 22 | 13 h 20 min |
| May | 67°F | 39°F | 53.2°F | 3.70 | 0.0 | 14 | <1 | 8 | 14 h 40 min |
| June | 75°F | 49°F | 61.9°F | 4.43 | 0.0 | 13 | 1 | <1 | 15 h 30 min |
| July | 80°F | 54°F | 67.1°F | 4.46 | 0.0 | 13 | 2 | <1 | 15 h 10 min |
| August | 79°F | 52°F | 65.2°F | 3.83 | 0.0 | 12 | 1 | <1 | 14 h |
| September | 72°F | 45°F | 58.2°F | 3.55 | 0.0 | 12 | <1 | 4 | 12 h 30 min |
| October | 58°F | 34°F | 46.0°F | 4.56 | 0.3 | 12 | <1 | 18 | 11 h 10 min |
| November | 46°F | 25°F | 35.2°F | 3.58 | 3.2 | 12 | <1 | 25 | 9 h 40 min |
| December | 34°F | 15°F | 24.3°F | 4.03 | 14.2 | 12 | <1 | 30 | 9 h |
| Year (annual) | 56°F | 31°F | 43.4°F | 44.45 | 68.3 | 141 | 5 | 196 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −14°C | −7.7°C | 81 mm | 46 cm |
| February | 1°C | −13°C | −6.3°C | 67 mm | 40 cm |
| March | 5°C | −8°C | −1.4°C | 80 mm | 34 cm |
| April | 13°C | −2°C | 5.4°C | 85 mm | 9 cm |
| May | 19°C | 4°C | 11.8°C | 94 mm | 0 cm |
| June | 24°C | 9°C | 16.6°C | 113 mm | 0 cm |
| July | 27°C | 12°C | 19.5°C | 113 mm | 0 cm |
| August | 26°C | 11°C | 18.4°C | 97 mm | 0 cm |
| September | 22°C | 7°C | 14.6°C | 90 mm | 0 cm |
| October | 15°C | 1°C | 7.8°C | 116 mm | 1 cm |
| November | 8°C | −4°C | 1.8°C | 91 mm | 8 cm |
| December | 1°C | −9°C | −4.3°C | 102 mm | 36 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00276945; 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 Plymouth?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (12).
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 USC00276945.
When is the last frost in Plymouth?
In Plymouth, the last spring frost (32°F) comes after May 20 in half of years and after June 4 in one year in ten; the first autumn frost comes before September 27 in half of years and before September 14 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 201 year in 10 after June 4; 9 in 10 after May 6
- First autumn frost, half of years before
- September 271 year in 10 before September 14; 9 in 10 before October 7
NOAA puts the median frost-free season at 128 days, and the season without a hard freeze (28°F) at 151 days.
A hard freeze (28°F) comes after May 7 in half of springs and before October 6 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Plymouth in zone 5b in ZIP code 03264. By the map's own method, the average of each year's coldest night over 1991-2020, Plymouth's NOAA station is in zone 5a: the coldest night of a typical year reaches −17°F (16 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 New Hampshire · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00276945; 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 Plymouth?
In a normal year in Plymouth, 5 days a year reach 90°F, 196 nights fall to 32°F or colder and 141 days bring measurable precipitation.
- Days at 90°F or more
- 5a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 196a normal year
- Days that stay below freezing
- 53high of 32°F or less
- Days with 0.01 inch of precipitation
- 141a normal year
- Days with 1 inch of snow or more
- 20a normal year
The highest temperature in this station's record (since 1951) is 98°F, on July 23, 1952; the lowest is −35°F, on January 21, 1994.
The wettest calendar year on that record is 2005, with 55.84 in; the snowiest season is 1968–69, with 127.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00276945; records: ACIS (NOAA Regional Climate Centers), station USC00276945. Records use complete months only; a month missing more than three days is left out.
How sunny is Plymouth?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Plymouth, 3.7 kWh per square metre a day. August is the sunniest month (77%) and December the cloudiest (62%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 1.7 |
| February | 68% | 2.5 |
| March | 68% | 3.6 |
| April | 68% | 4.6 |
| May | 67% | 5.2 |
| June | 70% | 5.6 |
| July | 76% | 5.8 |
| August | 77% | 5.2 |
| September | 77% | 4.2 |
| October | 66% | 2.7 |
| November | 66% | 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 Plymouth need?
A normal year in Plymouth brings 8,072 heating degree days, 50% more than the median U.S. place (5,373), and 242 cooling degree days, 73% 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 1,837 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,454 | 0 |
| February | 1,242 | 0 |
| March | 1,101 | 0 |
| April | 698 | 1 |
| May | 371 | 5 |
| June | 136 | 43 |
| July | 40 | 104 |
| August | 64 | 70 |
| September | 223 | 19 |
| October | 590 | 1 |
| November | 893 | 0 |
| December | 1,262 | 0 |
| Year (annual) | 8,072 | 242 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00276945. 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 Plymouth's climate compare?
Plymouth is warmer than 6 of the other 27 places with their own NOAA record in New Hampshire, and wetter than 12. Across the 7,247 U.S. stations with normals, its annual mean of 43.4°F is warmer than 13%.
In the Köppen classification computed from these normals, Plymouth 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 Plymouth share this climate record?
Ashland 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.
- Ashland, NH1,954 people · 6 mi S
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 Plymouth's climate
What is the coldest month in Plymouth?
January, with a normal high of 29°F and a normal low of 7°F. The warmest is July (80°F by day, 54°F at night).
Does it snow in Plymouth?
Yes: 68 inches in a normal year, falling on 31 days with 0.1 inch or more, the most in January (18.0 inches).
What is the rainiest month in Plymouth?
October, with 4.56 in of precipitation in a normal year; the driest is February with 2.62 in.
What plant hardiness zone is Plymouth in?
The USDA's 2023 map puts Plymouth in zone 5b in ZIP code 03264. By the same method at Plymouth's NOAA station, the coldest night of a typical year reaches −17°F (16 years, 1991-2020): zone 5a.
How late can frost come in Plymouth?
In half of years the last 32°F night comes after May 20; in one year in ten it comes after June 4. Waiting until June 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- New Hampshire climateThe statewide normals and every place in the state
- Meredith, NH11 miles from this station, 46.5°F a year
- Waterville Valley Nepp, NH13 miles from this station, 41.9°F a year
- Wentworth, NH14 miles from this station, 44.3°F a year
- East Sandwich, NH16 miles from this station, 44.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made