Photo: Smallbones · Public domainUnionville gets more rain and snow than 81% of U.S. towns: 49 inches of precipitation a year
Midsummer highs settle at about 86°. Decade by decade the climate has edged up, 1.8° above 1901–2000. Seedlings are safe outdoors from about April 19, with the first autumn frost due around October 26.
A year in Unionville at a glance
Each month’s typical high and low, and what it brings.
What stands out about Unionville’s climate
Compared with towns across the U.S., with Unionville’s place in Pennsylvania beside it.
What a year in Unionville feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 189 frost-free days a year
In half of years the last 32° night comes by April 19 and the first by October 26. Frost and day counts come from NOAA’s station at Avondale 2 N, PA, 4 miles from the town’s center, at about the same height.
The 2023 USDA map puts Unionville’s center in zone 7a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 3°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 32 inches of snow a winter
Snow, measured at Coatesville 2 W, PA, falls mostly in February. Precipitation (rain plus melted snow) adds up to 49 inches a year; September is the wettest month and February the driest. Rain or snow falls on about 131 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Unionville
87% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Avondale 2 N, PA.
Living with Unionville’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
189 frost-free days in zone 7a. The last frost comes by Apr 19 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 26.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 0.9 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Unionville from natural hazards, river flooding is the largest share (59%); heat waves, cold waves, winter storms and ice storms together are 9%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Unionville and its neighbors
Every town next door is within a degree of Unionville in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Unionville’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Unionville, PA | 23° | 86° | 49" | 32" |
| Staples, CT | 23° | 84° | 49" | 34" |
| New Martinsville, WV | 22° | 85° | 46" | 27" |
| Walton, KY | 23° | 86° | 47" | 23" |
| Amelia, OH | 23° | 86° | 46" | 23" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Unionville averaged 1.8° warmer than the 1900s. The biggest change is in December (+3.4°).
A bigger shift than in 82% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Unionville compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Unionville’s place among Pennsylvania’s.
Unionville weather by month
Highs, lows and precipitation from NOAA’s grid at Unionville’s center; snow, wet days and snow on the ground from Coatesville 2 W, PA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 40° | 23° | 3.6" | 7.9" | 12 | 11 | 23° – 39° |
| February | 43° | 24° | 2.9" | 11.5" | 10 | 13 | 23° – 41° |
| March | 51° | 31° | 4.4" | 6.3" | 12 | 5 | 36° – 50° |
| April | 64° | 41° | 3.8" | 1.1" | 12 | 0 | 48° – 57° |
| May | 73° | 50° | 3.9" | 0.0" | 11 | 0 | 57° – 68° |
| June | 81° | 60° | 4.4" | 0.0" | 11 | 0 | 67° – 75° |
| July | 86° | 65° | 4.8" | 0.0" | 11 | 0 | 72° – 79° |
| August | 84° | 63° | 4.5" | 0.0" | 10 | 0 | 69° – 77° |
| September | 77° | 56° | 5.0" | 0.0" | 10 | 0 | 64° – 71° |
| October | 66° | 44° | 4.3" | 0.0" | 9 | 0 | 50° – 61° |
| November | 54° | 35° | 3.4" | 0.7" | 10 | 1 | 39° – 49° |
| December | 45° | 27° | 4.2" | 4.4" | 11 | 6 | 28° – 48° |
| Year | 64° | 43° | 49.0" | 31.9" | 131 | 35 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 28° to 48°. September is the most reliable, staying within 7°.
Where Unionville’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Unionville’s center.
- Snow: Coatesville 2 W, PA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Avondale 2 N, PA, 4 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Unionville’s climate
What is the weather like in Unionville?
A typical July afternoon reaches 86°, a January night drops to 23°, and about 32 inches of snow falls in a normal winter. Milder January nights than 54% of U.S. towns; hotter July afternoons than 56% of U.S. towns.
How cold does it get in Unionville in winter?
January nights average 23°. About 109 nights a year reach 32° or below and 1 reach 0° or below. In the coldest January of the last 30 years the month averaged 23°.
How much snow does Unionville get?
About 32 inches in a normal winter at Coatesville 2 W, PA, most of it in February, with snow on the ground about 35 days a year.
How hot does it get in Unionville?
July, with a typical high of 86° and a low of 65°. About 8 days a year reach 90° (Avondale 2 N, PA).
When is the first and last frost in Unionville?
In half of years the last spring frost (32°) comes by April 19 and the first fall frost by October 26, about 189 frost-free days, at Avondale 2 N, PA.
What growing zone is Unionville in?
Zone 7a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 3°.
What is the best time of year to visit Unionville?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Unionville getting warmer?
Yes: 1991–2020 averaged 1.8° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 82% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Unionville.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.