Summers, winters and rain in Jefferson all run close to those of most U.S. towns
The depth of winter brings overnight lows near 21°. By precipitation alone, it ranks wetter than 62% of U.S. towns. December has warmed most since 1901–2000, part of a 1.7° rise. Long walks are most pleasant from May to June and August to October, when afternoons reach 65–83°.
A year in Jefferson at a glance
Each month’s typical high and low, and what it brings.
What stands out about Jefferson’s climate
Compared with towns across the U.S., with Jefferson’s place in Pennsylvania beside it.
What a year in Jefferson feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 188 frost-free days a year
In half of years the last 32° night comes by April 19 and the first by October 25. Frost and day counts come from NOAA’s station at Millers 4 Ne, MD, 7 miles from the town’s center, at about the same height.
The 2023 USDA map puts Jefferson’s center in zone 7a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 2°. 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 29 inches of snow a winter
Snow, measured at Spring Grove, PA, is heaviest from January through February, about 10 inches a month. Precipitation (rain plus melted snow) adds up to 46 inches a year; September is the wettest month and February the driest. Rain or snow falls on about 124 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Jefferson
84% of the work is heating. 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 Millers 4 Ne, MD.
Living with Jefferson’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
188 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 25.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October.
Parks & trails →Of the yearly building losses FEMA expects in Jefferson from natural hazards, river flooding is the largest share (62%); heat waves, cold waves, winter storms and ice storms together are 9%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Jefferson and its neighbors
Every town next door is within a degree of Jefferson in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Jefferson’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 |
|---|---|---|---|---|
| Jefferson, PA | 21° | 85° | 46" | 29" |
| New Martinsville, WV | 22° | 85° | 46" | 27" |
| Cumberland, IN | 20° | 85° | 44" | 27" |
| Oxford, OH | 21° | 85° | 44" | 25" |
| Clarkstown, NY | 21° | 85° | 48" | 33" |
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 Jefferson averaged 1.7° warmer than the 1900s. The biggest change is in December (+3.0°).
A bigger shift than in 75% 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 Jefferson compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Jefferson’s place among Pennsylvania’s.
Jefferson weather by month
Highs, lows and precipitation from NOAA’s grid at Jefferson’s center; snow, wet days and snow on the ground from Spring Grove, PA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 39° | 21° | 3.2" | 9.8" | 11 | 8 | 21° – 38° |
| February | 42° | 23° | 2.7" | 9.4" | 9 | 10 | 21° – 41° |
| March | 51° | 30° | 4.0" | 5.0" | 11 | 5 | 35° – 50° |
| April | 63° | 40° | 3.6" | 0.2" | 12 | 0 | 47° – 57° |
| May | 73° | 50° | 4.0" | 0.0" | 13 | 0 | 56° – 67° |
| June | 81° | 59° | 4.1" | 0.0" | 11 | 0 | 66° – 73° |
| July | 85° | 64° | 4.6" | 0.0" | 10 | 0 | 70° – 78° |
| August | 83° | 62° | 3.8" | 0.0" | 10 | 0 | 68° – 76° |
| September | 77° | 55° | 4.9" | 0.0" | 9 | 0 | 63° – 69° |
| October | 65° | 43° | 4.0" | 0.0" | 9 | 0 | 50° – 61° |
| November | 53° | 33° | 3.2" | 0.6" | 9 | 0 | 37° – 48° |
| December | 43° | 26° | 3.6" | 3.8" | 10 | 4 | 26° – 46° |
| Year | 63° | 42° | 45.5" | 28.8" | 124 | 27 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 26° to 46°. September is the most reliable, staying within 7°.
Where Jefferson’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 Jefferson’s center.
- Snow: Spring Grove, PA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Millers 4 Ne, MD, 7 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 Jefferson’s climate
What is the weather like in Jefferson?
A typical July afternoon reaches 85°, a January night drops to 21°, and about 29 inches of snow falls in a normal winter. Colder January nights than 53% of U.S. towns; hotter July afternoons than 51% of U.S. towns.
How cold does it get in Jefferson in winter?
January nights average 21°. About 101 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 21°.
How much snow does Jefferson get?
About 29 inches in a normal winter at Spring Grove, PA, heaviest from January through February, about 10 inches a month, with snow on the ground about 27 days a year.
How hot does it get in Jefferson?
July, with a typical high of 85° and a low of 64°. About 12 days a year reach 90° (Millers 4 Ne, MD).
When is the first and last frost in Jefferson?
In half of years the last spring frost (32°) comes by April 19 and the first fall frost by October 25, about 188 frost-free days, at Millers 4 Ne, MD.
What growing zone is Jefferson in?
Zone 7a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 2°.
What is the best time of year to visit Jefferson?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Jefferson getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 75% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Jefferson.
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.