West Chester, Pennsylvania climate: Normal weather by month, frost dates and records
West Chester's normal year runs from 20°F January nights to 86°F July afternoons, with 50.9 inches of precipitation and 31 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.3°C, January lows of −7°C, July highs of 30°C, 1,294 mm of precipitation a year.
- NOAA stationWest Chester (2 mi NW)
- Station IDUSC00369464
- Location39.97°N 75.64°W
- Elevation375 ft (114 m)
- From the center2 miles
- Population22,758
On October 14, the normal high in West Chester is 67°F and the normal low 42°F, and the chance of measurable rain or snow is 34%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for West Chester.
- Jan 40° 20°
- Feb 43° 21°
- Mar 51° 29°
- Apr 63° 38°
- May 73° 49°
- Jun 82° 59°
- Jul 86° 64°
- Aug 84° 62°
- Sep 78° 54°
- Oct 66° 41°
- Nov 55° 32°
- Dec 44° 25°
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 West Chester each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 20°F. The most precipitation falls in September (5.65 in), the least in February (3.12 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 | 20°F | 29.6°F | 3.65 | 7.9 | 11 | <1 | 27 | 9 h 40 min |
| February | 43°F | 21°F | 31.9°F | 3.12 | 13.2 | 9 | <1 | 25 | 10 h 40 min |
| March | 51°F | 29°F | 39.8°F | 4.61 | 4.1 | 11 | <1 | 21 | 11 h 50 min |
| April | 63°F | 38°F | 50.7°F | 3.78 | 0.4 | 11 | 1 | 9 | 13 h 10 min |
| May | 73°F | 49°F | 60.8°F | 3.81 | 0.0 | 11 | 2 | 1 | 14 h 20 min |
| June | 82°F | 59°F | 70.4°F | 4.01 | 0.0 | 11 | 6 | <1 | 15 h |
| July | 86°F | 64°F | 75.0°F | 4.41 | 0.0 | 10 | 10 | <1 | 14 h 50 min |
| August | 84°F | 62°F | 73.0°F | 4.79 | 0.0 | 10 | 7 | <1 | 13 h 50 min |
| September | 78°F | 54°F | 65.9°F | 5.65 | 0.0 | 9 | 2 | <1 | 12 h 30 min |
| October | 66°F | 41°F | 53.7°F | 4.83 | 0.0 | 11 | <1 | 6 | 11 h 10 min |
| November | 55°F | 32°F | 43.4°F | 3.55 | 0.5 | 10 | <1 | 17 | 10 h |
| December | 44°F | 25°F | 34.8°F | 4.72 | 4.4 | 11 | <1 | 25 | 9 h 20 min |
| Year (annual) | 64°F | 41°F | 52.4°F | 50.93 | 30.5 | 124 | 27 | 131 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −7°C | −1.3°C | 93 mm | 20 cm |
| February | 6°C | −6°C | −0.1°C | 79 mm | 34 cm |
| March | 11°C | −2°C | 4.3°C | 117 mm | 10 cm |
| April | 17°C | 3°C | 10.4°C | 96 mm | 1 cm |
| May | 23°C | 9°C | 16.0°C | 97 mm | 0 cm |
| June | 28°C | 15°C | 21.3°C | 102 mm | 0 cm |
| July | 30°C | 18°C | 23.9°C | 112 mm | 0 cm |
| August | 29°C | 16°C | 22.8°C | 122 mm | 0 cm |
| September | 26°C | 12°C | 18.8°C | 144 mm | 0 cm |
| October | 19°C | 5°C | 12.1°C | 123 mm | 0 cm |
| November | 13°C | 0°C | 6.3°C | 90 mm | 1 cm |
| December | 7°C | −4°C | 1.6°C | 120 mm | 11 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00369464; 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 West Chester?
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 USC00369464.
When is the last frost in West Chester?
In West Chester, the last spring frost (32°F) comes after April 26 in half of years and after May 11 in one year in ten; the first autumn frost comes before October 18 in half of years and before October 4 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 261 year in 10 after May 11; 9 in 10 after April 10
- First autumn frost, half of years before
- October 181 year in 10 before October 4; 9 in 10 before November 1
NOAA puts the median frost-free season at 174 days, and the season without a hard freeze (28°F) at 198 days.
A hard freeze (28°F) comes after April 11 in half of springs and before October 30 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts West Chester in zone 7a in ZIP code 19383, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, West Chester's NOAA station is in zone 7a: the coldest night of a typical year reaches 1°F (17 complete years).
Frost dates for every NOAA station in Pennsylvania · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00369464; 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 West Chester?
In a normal year in West Chester, 27 days a year reach 90°F (1 of them 100°F or more), 131 nights fall to 32°F or colder and 124 days bring measurable precipitation.
- Days at 90°F or more
- 27a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 131a normal year
- Days that stay below freezing
- 17high of 32°F or less
- Days with 0.01 inch of precipitation
- 124a normal year
- Days with 1 inch of snow or more
- 6a normal year
The highest temperature in this station's record (since 1893) is 105°F, on July 10, 1936; the lowest is −16°F, on January 22, 1984.
The wettest calendar year on that record is 2003, with 71.48 in; the snowiest season is 2009–10, with 64.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00369464; records: ACIS (NOAA Regional Climate Centers), station USC00369464. Records use complete months only; a month missing more than three days is left out.
How sunny is West Chester?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around West Chester, 4.1 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (68%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 2.0 |
| February | 71% | 2.9 |
| March | 69% | 3.8 |
| April | 73% | 5.0 |
| May | 72% | 5.6 |
| June | 78% | 6.2 |
| July | 82% | 6.2 |
| August | 80% | 5.4 |
| September | 77% | 4.4 |
| October | 73% | 3.2 |
| November | 74% | 2.3 |
| December | 68% | 1.8 |
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 West Chester need?
A normal year in West Chester brings 5,478 heating degree days, 2% more than the median U.S. place (5,373), and 918 cooling degree days, 1% 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 3,270 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,097 | 0 |
| February | 928 | 0 |
| March | 781 | 0 |
| April | 440 | 9 |
| May | 182 | 52 |
| June | 26 | 186 |
| July | 1 | 310 |
| August | 5 | 252 |
| September | 72 | 98 |
| October | 359 | 11 |
| November | 650 | 0 |
| December | 936 | 0 |
| Year (annual) | 5,478 | 918 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00369464. 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 West Chester been warmer than normal lately?
Over 118 complete years from 1855 to 2016, the station's annual mean temperature rose at a fitted 3.3°F per century (+0.18°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does West Chester's climate compare?
West Chester is warmer than 83 of the other 107 places with their own NOAA record in Pennsylvania, and wetter than 98. Across the 7,247 U.S. stations with normals, its annual mean of 52.4°F is warmer than 51%.
In the Köppen classification computed from these normals, West Chester 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 West Chester share this climate record?
5 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.
- Downingtown, PA8,463 people · 4 mi NW
- Lionville, PA7,091 people · 6 mi N
- Exton, PA6,192 people · 4 mi N
- Frazer, PA3,498 people · 6 mi NE
- Marshallton, PA491 people · 3 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.
Questions about West Chester's climate
What is the coldest month in West Chester?
January, with a normal high of 40°F and a normal low of 20°F. The warmest is July (86°F by day, 64°F at night).
Does it snow in West Chester?
Yes: 31 inches in a normal year, falling on 14 days with 0.1 inch or more, the most in February (13.2 inches).
What is the rainiest month in West Chester?
September, with 5.65 in of precipitation in a normal year; the driest is February with 3.12 in.
What plant hardiness zone is West Chester in?
The USDA's 2023 map puts West Chester in zone 7a in ZIP code 19383, the nearest ZIP area. By the same method at West Chester's NOAA station, the coldest night of a typical year reaches 1°F (17 years, 1991-2020): zone 7a.
How late can frost come in West Chester?
In half of years the last 32°F night comes after April 26; in one year in ten it comes after May 11. Waiting until May 11 leaves about a one-in-ten chance of a later frost.
Nearby and next
- West Chester in OctoberThis month day by day, its records and recent years
- Pennsylvania climateThe statewide normals and every place in the state
- Glenmoore, PA11 miles from this station, 52.5°F a year
- Avondale, PA11 miles from this station, 52.3°F a year
- Coatesville, PA12 miles from this station, 52.8°F a year
- Phoenixville, PA13 miles from this station, 54.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made