Somerville, NJ Climate: Temperature & Rain by Month
Pulled from NOAA NCEI 1991–2020 normals →: climate measurements used in PlainClimate's documented score
30-year climate normals (1991-2020) from Somerville's primary NOAA station, SOMERVILLE 4 NW.
The climate verdict for Somerville
Water is the standout signal in Somerville, New Jersey: 46.7 inches of precipitation in a normal year. Against that wet profile, NOAA records an annual average of 51°F. Its climate comfort score of 64/100 (good) lands mid-pack nationally, exceeding 49% of station-mapped location scores.
- 51°F
- yearly average temperature, NOAA normal
- 64/100
- comfort score, above 49% of station-mapped location scores
- 46.7"
- precipitation, annual total
- 173 days
- growing season, frost-free days
Somerville: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00288194 · Somerville, NJ 51°F mean · 46.7" precip
TEMP-COOL · RANK-MID · PHOTO-FINISH · PRCP-MID · SWING-MID · COMF-MID · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 51°F
- RANK-MID #3,087
- PHOTO-FINISH ≈ Selinsgrove Pen…
- PRCP-MID 46.7"
- SWING-MID 45°F
- COMF-MID 64/100
- LOAD-HEAT 5,769 HDD
- STN-1 USC00288194
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Selinsgrove Penn Vly, PA (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every NJ station list.
- Somerville (this station) 51°F
- Hot Landisville, PA 51°F
- Near Selinsgrove Pen…, PA 51°F
- Near Taunton, MA 51°F
- Near Woonsocket, RI 51°F
Climate Living Index · Somerville
Somerville: 50/100 · grade D
Somerville publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Somerville, not an official NOAA rating. Rankings still use Comfort Score 64/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 46.7 in · 11.7 from 35 in | 59/100 · C |
| Normal heat + freeze calendar | 142 calendar days | 52/100 · D |
| Annual temperature balance | 51.1°F · 16.4° from 67.5°F | 45/100 · D |
| Frost-free season | 173 days/year | 44/100 · D |
Somerville · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Somerville is a continental Köppen climate: Dfa
Coldest-month mean 29.0°F and warmest-month mean 73.7°F place this station in continental, no dry season, hot summer climates (Dfa). Class Dfa is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, hot summer.
- Köppen code
- Dfa
- Group
- Continental
- Warmest month
- 73.7°F
- Coldest month
- 29.0°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Somerville sits across the climate record
Three NOAA fields for Somerville's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 45th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Top 28% wettest
- Somerville's annual total ranks in the wetter third of 6,352 measured normals.
- Seasonal temperature swing
- 57th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Somerville compares across U.S. station-mapped locations
Somerville's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
64 49th percentile score exceeds 49% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). This entry sits in this band.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 39°F (4°C) | 19°F (-7°C) | 29°F (-2°C) | 3.5" | 27.9 | 0.0 |
| February | 41°F (5°C) | 20°F (-7°C) | 30°F (-1°C) | 2.8" | 25.4 | 0.0 |
| March | 50°F (10°C) | 27°F (-3°C) | 38°F (4°C) | 4.1" | 22.7 | 0.0 |
| April | 62°F (17°C) | 36°F (2°C) | 49°F (10°C) | 4.0" | 9.8 | 0.1 |
| May | 72°F (22°C) | 46°F (8°C) | 59°F (15°C) | 3.4" | 1.1 | 0.8 |
| June | 81°F (27°C) | 56°F (13°C) | 68°F (20°C) | 4.3" | 0.0 | 3.3 |
| July | 86°F (30°C) | 62°F (17°C) | 74°F (23°C) | 4.7" | 0.0 | 7.0 |
| August | 83°F (29°C) | 60°F (16°C) | 72°F (22°C) | 3.7" | 0.0 | 4.4 |
| September | 77°F (25°C) | 53°F (12°C) | 65°F (18°C) | 4.3" | 0.0 | 0.7 |
| October | 64°F (18°C) | 41°F (5°C) | 53°F (12°C) | 4.3" | 6.4 | 0.0 |
| November | 54°F (12°C) | 31°F (0°C) | 42°F (6°C) | 3.2" | 18.1 | 0.0 |
| December | 43°F (6°C) | 24°F (-4°C) | 34°F (1°C) | 4.4" | 25.3 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 86°F around July 10, short of 90°F on every date, while 142 dates carry a normal low at or below freezing, the coldest 18°F near January 30.
The freezing stretch
The normal low stays at or below 32°F into April 1, then returns to freezing around November 12, covering 142 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is April 9, when 40% of years recorded at least a hundredth of an inch. The driest is October 27 at 26%. Summed across the calendar, that is about 123 wet dates a year.
The widest day
April 27 carries the biggest normal gap between afternoon and dawn, 27°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Somerville.
Monthly Precipitation
Average monthly rainfall
11.2 days with precipitation
9.2 days with precipitation
11.7 days with precipitation
11.7 days with precipitation
11.9 days with precipitation
10.1 days with precipitation
10.2 days with precipitation
9.7 days with precipitation
8.7 days with precipitation
8.2 days with precipitation
8.6 days with precipitation
11.2 days with precipitation
Somerville spreads its precipitation across the year
Neither half of the year dominates here: June through August take 27% of the annual total and December through February 23%, with neither reaching the 35% that would mark a distinct wet season. Somerville has no dry season to plan around, though it does carry a 44.7°F seasonal spread.
The gap between the wettest and driest month still matters: July averages 4.7" and February 2.8". The three wettest months together take 29% of the year, against the 25% a perfectly flat distribution would give them.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. "Spread across the year" means neither the June-August nor the December-February share reaches 35%; it describes an average year, not the variability of any single one.
When it rains in Somerville, it arrives in quantity
46.7" of precipitation falls across only about 122 wet days here, averaging 0.38 inches each. Fewer days carry more water: the year's total is delivered in comparatively heavy events rather than persistent damp.
- Days with measurable precipitation
- about 122 a year, 34% of all days
- Average depth per wet day
- 0.38 inches
- Most wet days
- May, about 12
- Fewest wet days
- October, about 8
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, and a per-day average is not a forecast of any individual storm.
Frost Dates & Growing Season
First Fall Freeze
October 20
50% probability date
Last Spring Freeze
April 30
50% probability date
Growing Season
173 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,769
Higher = more heating needed
Cooling Degree Days
748
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside NJ closest to Somerville on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (51°F here).
- Alpine, UT 51°F · 0.0°F off
- Baiting Hollow, NY 51°F · 0.0°F off
- Burr Oak, KS 51°F · 0.0°F off
- Cambridge, NE 51°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (46.7" here), excluding temperature-peer places.
- Ashland, KY 46.7" · 0.0" off
- Hillsboro, OH 46.7" · 0.0" off
- Hot Springs, NC 46.7" · 0.0" off
- Fulton, NY 46.7" · 0.0" off
Data-derived climate profile
How Somerville's climate pattern fits together
heating led · wet · mid swing
Somerville's energy balance leans toward cold weather: 5,769 annual heating degree days against 748 for cooling. Its 44.7°F seasonal range still makes the monthly rows more useful than the annual average alone.
Somerville's frost-free season lasts about 173 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
July and January mark the typical warm and cold ends of the calendar in Somerville's middle-range seasonal profile. The measured spread is 44.7°F. The annual average is 51°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Alongside its heating load, Somerville carries 46.7 inches of precipitation in a normal year, inside PlainClimate's wet range. Snowfall is not added to the interpretation because its annual value is missing. That distinction matters because a wet annual total can arrive as rain, snow, or a mixture at different times.
These labels group NOAA 1991-2020 normals from Somerville's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Somerville, not an official NOAA class or a year-ahead forecast.
Questions about Somerville's climate
How much rain does Somerville get? ▼
How cold does Somerville get in winter? ▼
How much energy does heating and cooling require in Somerville? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Somerville's primary station: SOMERVILLE 4 NW (USC00288194). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 3468460). Match rule for Somerville: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Somerville comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.