Trenton, New Jersey climate: Normal weather by month, frost dates and records
Trenton's normal year runs from 24°F January nights to 86°F July afternoons, with 45.6 inches of precipitation and 27 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.3°C, January lows of −4°C, July highs of 30°C, 1,159 mm of precipitation a year.
- NOAA stationTrenton-Mercer Airport
- Station IDUSW00014792
- Location40.28°N 74.82°W
- Elevation184 ft (56 m)
- From the center5 miles
- Population91,193
On October 14, the normal high in Trenton is 66°F and the normal low 47°F, and the chance of measurable rain or snow is 32%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Trenton.
- Jan 40° 24°
- Feb 43° 26°
- Mar 51° 33°
- Apr 63° 42°
- May 72° 52°
- Jun 81° 61°
- Jul 86° 67°
- Aug 84° 65°
- Sep 77° 58°
- Oct 66° 46°
- Nov 55° 36°
- Dec 44° 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 Trenton each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 24°F. The most precipitation falls in July (4.42 in), the least in February (2.65 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 | 40°F | 24°F | 32.0°F | 3.29 | 8.2 | 10 | <1 | 25 | 9 h 40 min |
| February | 43°F | 26°F | 34.3°F | 2.65 | 8.7 | 10 | <1 | 22 | 10 h 40 min |
| March | 51°F | 33°F | 41.7°F | 4.00 | 4.0 | 11 | <1 | 15 | 11 h 50 min |
| April | 63°F | 42°F | 52.5°F | 3.63 | 0.5 | 12 | <1 | 3 | 13 h 10 min |
| May | 72°F | 52°F | 62.0°F | 3.99 | 0.0 | 12 | 1 | <1 | 14 h 20 min |
| June | 81°F | 61°F | 71.0°F | 4.35 | 0.0 | 12 | 4 | <1 | 15 h |
| July | 86°F | 67°F | 76.3°F | 4.42 | 0.0 | 11 | 9 | <1 | 14 h 50 min |
| August | 84°F | 65°F | 74.4°F | 4.22 | 0.0 | 10 | 6 | <1 | 13 h 50 min |
| September | 77°F | 58°F | 67.4°F | 4.05 | 0.0 | 9 | 2 | <1 | 12 h 30 min |
| October | 66°F | 46°F | 55.7°F | 3.79 | 0.1 | 10 | <1 | 1 | 11 h 10 min |
| November | 55°F | 36°F | 45.4°F | 3.20 | 0.5 | 9 | <1 | 10 | 10 h |
| December | 44°F | 29°F | 36.8°F | 4.04 | 4.6 | 11 | <1 | 22 | 9 h 20 min |
| Year (annual) | 63°F | 45°F | 54.1°F | 45.63 | 26.6 | 126 | 22 | 97 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −4°C | 0.0°C | 84 mm | 21 cm |
| February | 6°C | −3°C | 1.3°C | 67 mm | 22 cm |
| March | 10°C | 0°C | 5.4°C | 102 mm | 10 cm |
| April | 17°C | 6°C | 11.4°C | 92 mm | 1 cm |
| May | 22°C | 11°C | 16.7°C | 101 mm | 0 cm |
| June | 27°C | 16°C | 21.7°C | 110 mm | 0 cm |
| July | 30°C | 19°C | 24.6°C | 112 mm | 0 cm |
| August | 29°C | 18°C | 23.6°C | 107 mm | 0 cm |
| September | 25°C | 14°C | 19.7°C | 103 mm | 0 cm |
| October | 19°C | 8°C | 13.2°C | 96 mm | 0 cm |
| November | 13°C | 2°C | 7.4°C | 81 mm | 1 cm |
| December | 7°C | −1°C | 2.7°C | 103 mm | 12 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014792; 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 Trenton?
Normal highs sit between 65°F and 85°F in May, June, August, September and October. Of those, September 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 USW00014792.
When is the last frost in Trenton?
In Trenton, the last spring frost (32°F) comes after April 10 in half of years and after April 25 in one year in ten; the first autumn frost comes before November 1 in half of years and before October 15 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 101 year in 10 after April 25; 9 in 10 after March 30
- First autumn frost, half of years before
- November 11 year in 10 before October 15; 9 in 10 before November 13
NOAA puts the median frost-free season at 202 days, and the season without a hard freeze (28°F) at 226 days.
A hard freeze (28°F) comes after March 31 in half of springs and before November 12 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Trenton in zones 7a to 7b across its 5 ZIP code areas (7b in 08618, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Trenton's NOAA station is in zone 7b: the coldest night of a typical year reaches 6°F (22 complete years).
Frost dates for every NOAA station in New Jersey · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00014792; 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 Trenton ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Trenton's 5 ZIP code areas run from zone 7a to 7b: 4 in 7a and 1 in 7b. Each ZIP's frost dates are in the frost tool.
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 Trenton?
In a normal year in Trenton, 22 days a year reach 90°F (1 of them 100°F or more), 97 nights fall to 32°F or colder and 126 days bring measurable precipitation.
- Days at 90°F or more
- 22a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 97a normal year
- Days that stay below freezing
- 17high of 32°F or less
- Days with 0.01 inch of precipitation
- 126a normal year
- Days with 1 inch of snow or more
- 7a normal year
The highest temperature in Trenton's official record (kept by the National Weather Service since 1865) is 106°F, on July 9, 1936; the lowest is −16°F, on January 22, 1984.
The wettest calendar year on that record is 1996, with 67.46 in; the snowiest season is 1995–96, with 76.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00014792; records: ACIS (NOAA Regional Climate Centers), NWS threaded record TTNthr. Records use complete months only; a month missing more than three days is left out.
How sunny is Trenton?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Trenton, 3.9 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (66%). Among the 459 U.S. places of 50,000 or more, that ranks tied 352nd (with 32 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 1.9 |
| February | 71% | 2.8 |
| March | 69% | 3.7 |
| April | 71% | 4.8 |
| May | 70% | 5.4 |
| June | 76% | 6.0 |
| July | 80% | 6.0 |
| August | 78% | 5.2 |
| September | 76% | 4.3 |
| October | 71% | 3.0 |
| November | 72% | 2.2 |
| December | 66% | 1.6 |
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 Trenton need?
A normal year in Trenton brings 4,977 heating degree days, 7% fewer than the median U.S. place (5,373), and 1,050 cooling degree days, 16% more 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 3,551 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,023 | 0 |
| February | 858 | 0 |
| March | 722 | 1 |
| April | 387 | 12 |
| May | 148 | 55 |
| June | 20 | 199 |
| July | 0 | 351 |
| August | 2 | 294 |
| September | 51 | 123 |
| October | 304 | 16 |
| November | 588 | 0 |
| December | 873 | 0 |
| Year (annual) | 4,977 | 1,050 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00014792. 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 Trenton been warmer than normal lately?
2025 averaged 53.7°F, 0.4°F below the 1991-2020 normal of 54.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 55.1°F | +1.0°F | 43.00 | 27.3 |
| 2022 | 54.2°F | +0.1°F | 43.87 | 16.4 |
| 2023 | 55.3°F | +1.2°F | 44.93 | 2.0 |
| 2024 | 55.8°F | +1.7°F | 41.25 | 19.2 |
| 2025 | 53.7°F | −0.4°F | 34.55 | 18.1 |
Source: observed years: ACIS, station USW00014792. A year counts only with all twelve months complete.
How does Trenton's climate compare?
Trenton is warmer than 17 of the other 32 places with their own NOAA record in New Jersey, and wetter than 5. Across the 7,247 U.S. stations with normals, its annual mean of 54.1°F is warmer than 57%.
In the Köppen classification computed from these normals, Trenton is Cfa: temperate, 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 Trenton share this climate record?
16 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.
- Levittown, PAalso near: Neshaminy Falls (5 mi, 52.9°F a year); Philadelphia NE Airport (10 mi, 56.4°F a year)50,930 people · 9 mi S
- Morrisville, PA9,745 people · 5 mi S
- Fairless Hills, PA8,985 people · 7 mi S
- Churchville, PA6,139 people · 11 mi SW
- The College of New Jersey, NJ4,103 people · 2 mi E
- Lawrenceville, NJ3,947 people · 4 mi NE
- Village Shires, PA3,360 people · 10 mi SW
- Woodbourne, PA3,351 people · 6 mi SW
- Pennington, NJ2,906 people · 4 mi NE
- Woodside, PA2,676 people · 4 mi SW
- Yardley, PA2,591 people · 3 mi SW
- Penndel, PA2,525 people · 10 mi SW
- Newtown, PA2,272 people · 7 mi SW
- Langhorne, PA1,634 people · 9 mi SW
- Langhorne Manor, PA1,472 people · 9 mi SW
- Parkland, PA1,461 people · 10 mi SW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Trenton's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Trenton. This page uses Trenton-Mercer Airport; the other differs by site and elevation:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Trenton State College USC00288880 | 4 mi NW | 100 ft | 53.4°F | 23°F | 87°F | 47.4 | – | April 17 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Trenton's climate
What is the coldest month in Trenton?
January, with a normal high of 40°F and a normal low of 24°F. The warmest is July (86°F by day, 67°F at night).
Does it snow in Trenton?
Yes: 27 inches in a normal year, falling on 15 days with 0.1 inch or more, the most in February (8.7 inches).
What is the rainiest month in Trenton?
July, with 4.42 in of precipitation in a normal year; the driest is February with 2.65 in.
What plant hardiness zone is Trenton in?
The USDA's 2023 map puts Trenton in zones 7a to 7b across its 5 ZIP code areas (7b in 08618, the largest). By the same method at Trenton's NOAA station, the coldest night of a typical year reaches 6°F (22 years, 1991-2020): zone 7b.
How late can frost come in Trenton?
In half of years the last 32°F night comes after April 10; in one year in ten it comes after April 25. Waiting until April 25 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Trenton in OctoberThis month day by day, its records and recent years
- New Jersey climateThe statewide normals and every place in the state
- Lambertville, NJ9 miles from this station, 53.1°F a year
- Neshaminy Falls, PA11 miles from this station, 52.9°F a year
- Wertsville (4 mi NE), NJ12 miles from this station, 52.5°F a year
- Hightstown, NJ13 miles from this station, 52.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made