Photo: Nyttend · Public domainAfternoon heat in Portersville trails that of 76% of U.S. towns
On a normal January night the air cools to about 19°. In January, nights here are colder than in 66% of U.S. towns. December has warmed most since 1901–2000, part of a 1.4° rise. Seedlings are safe outdoors from about May 7, with the first autumn frost due around October 14.
A year in Portersville at a glance
Each month’s typical high and low, and what it brings.
What stands out about Portersville’s climate
Compared with towns across the U.S., with Portersville’s place in Pennsylvania beside it.
What a year in Portersville feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 158 frost-free days a year
In half of years the last 32° night comes by May 7 and the first by October 14. Frost and day counts come from NOAA’s station at Slippery Rock 1 Ssw, PA, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Portersville’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −6°. 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 35 inches of snow a winter
Snow, measured at Butler 2 Sw, PA, falls mostly in January. Precipitation (rain plus melted snow) adds up to 44 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 168 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Portersville
94% 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 Slippery Rock 1 Ssw, PA.
Living with Portersville’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
158 frost-free days in zone 6a. The last frost comes by May 7 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 14.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 0.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Portersville from natural hazards, river flooding is the largest share (83%); heat waves, cold waves, winter storms and ice storms together are 2%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Portersville and similar climates
TownRatings has no climate map of the towns around Portersville yet.
Climates most like Portersville’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 |
|---|---|---|---|---|
| Portersville, PA | 19° | 83° | 44" | 35" |
| Kokomo, IN | 18° | 84° | 42" | 34" |
| Chester, NY | 18° | 83° | 46" | 39" |
| Griswold, CT | 19° | 83° | 47" | 38" |
| Hopkinton, RI | 20° | 82° | 47" | 35" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Portersville averaged 1.4° warmer than the 1900s. The biggest change is in December (+2.7°).
A bigger shift than in 53% 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 Portersville compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Portersville’s place among Pennsylvania’s.
Portersville weather by month
Highs, lows and precipitation from NOAA’s grid at Portersville’s center; snow, wet days and snow on the ground from Butler 2 Sw, PA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 35° | 19° | 3.2" | 11.3" | 18 | 18 | 18° – 37° |
| February | 38° | 21° | 2.5" | 9.7" | 15 | 15 | 15° – 38° |
| March | 48° | 28° | 3.4" | 5.3" | 14 | 8 | 31° – 49° |
| April | 61° | 37° | 3.8" | 0.6" | 15 | 0 | 43° – 54° |
| May | 71° | 47° | 4.0" | 0.0" | 15 | 0 | 52° – 66° |
| June | 79° | 56° | 4.7" | 0.0" | 13 | 0 | 63° – 70° |
| July | 83° | 60° | 4.5" | 0.0" | 12 | 0 | 67° – 75° |
| August | 81° | 58° | 4.0" | 0.0" | 11 | 0 | 65° – 74° |
| September | 75° | 52° | 4.0" | 0.0" | 11 | 0 | 60° – 68° |
| October | 63° | 41° | 3.3" | 0.1" | 13 | 0 | 48° – 58° |
| November | 50° | 32° | 3.2" | 1.1" | 14 | 2 | 36° – 47° |
| December | 39° | 25° | 3.3" | 6.8" | 16 | 10 | 22° – 43° |
| Year | 60° | 40° | 43.8" | 34.9" | 168 | 53 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 15° to 38°. June is the most reliable, staying within 8°.
Where Portersville’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 Portersville’s center.
- Snow: Butler 2 Sw, PA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Slippery Rock 1 Ssw, PA, 10 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 Portersville’s climate
What is the weather like in Portersville?
A typical July afternoon reaches 83°, a January night drops to 19°, and about 35 inches of snow falls in a normal winter. Colder January nights than 66% of U.S. towns; cooler July afternoons than 76% of U.S. towns.
How cold does it get in Portersville in winter?
January nights average 19°. About 142 nights a year reach 32° or below and 6 reach 0° or below. In the coldest January of the last 30 years the month averaged 18°.
How much snow does Portersville get?
About 35 inches in a normal winter at Butler 2 Sw, PA, most of it in January, with snow on the ground about 53 days a year.
How hot does it get in Portersville?
July, with a typical high of 83° and a low of 60°. About 13 days a year reach 90° (Slippery Rock 1 Ssw, PA).
When is the first and last frost in Portersville?
In half of years the last spring frost (32°) comes by May 7 and the first fall frost by October 14, about 158 frost-free days, at Slippery Rock 1 Ssw, PA.
What growing zone is Portersville in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −6°.
What is the best time of year to visit Portersville?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Portersville getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 53% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Portersville.
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.