Photo: Shuvaev · CC BY-SA 3.0More precipitation falls on Roslyn than on 77% of U.S. towns: 48 inches a year
On a normal July day the thermometer tops out near 86°. The year swings widely: the coldest month’s nights and the warmest month’s afternoons are 63° apart. The frost-free window for a garden runs roughly April 11 to November 1.
A year in Roslyn at a glance
Each month’s typical high and low, and what it brings.
What stands out about Roslyn’s climate
Compared with towns across the U.S., with Roslyn’s place in Pennsylvania beside it.
What a year in Roslyn feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 205 frost-free days a year
In half of years the last 32° night comes by April 11 and the first by November 1. Frost and day counts come from NOAA’s station at Willow Grove Nas, PA, 5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Roslyn’s center in zone 7b: 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 8 inches of snow a winter
Snow, measured at Conshohocken, PA, falls mostly in January. Precipitation (rain plus melted snow) adds up to 48 inches a year; July is the wettest month and February the driest. Rain or snow falls on about 111 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Roslyn
83% of the work is heating. Months averaging under 55° run from November 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 Willow Grove Nas, PA.
Living with Roslyn’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
205 frost-free days in zone 7b. The last frost comes by Apr 11 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 1.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 0.4 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Roslyn from natural hazards, river flooding is the largest share (68%); heat waves, cold waves, winter storms and ice storms together are 20%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Roslyn and its neighbors
Every town next door is within a degree of Roslyn in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Roslyn’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 |
|---|---|---|---|---|
| Roslyn, PA | 24° | 86° | 48" | 7.6" |
| Danville, KY | 25° | 86° | 49" | 7.4" |
| Washington, IN | 22° | 87° | 48" | 9.2" |
| Huntington, WV | 25° | 87° | 46" | 10" |
| Elizabethton, TN | 26° | 86° | 47" | 6.0" |
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 Roslyn averaged 2.2° warmer than the 1900s. The biggest change is in December (+3.7°).
A bigger shift than in 95% 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 Roslyn compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Roslyn’s place among Pennsylvania’s.
Roslyn weather by month
Highs, lows and precipitation from NOAA’s grid at Roslyn’s center; snow, wet days and snow on the ground from Conshohocken, PA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 40° | 24° | 3.5" | 2.7" | 9 | 3 | 24° – 39° |
| February | 43° | 25° | 2.8" | 2.4" | 9 | 3 | 23° – 41° |
| March | 51° | 32° | 4.2" | 0.6" | 10 | 2 | 36° – 50° |
| April | 64° | 41° | 3.8" | 0.1" | 11 | 0 | 49° – 57° |
| May | 73° | 51° | 4.0" | 0.0" | 11 | 0 | 57° – 68° |
| June | 82° | 61° | 4.3" | 0.0" | 9 | 0 | 68° – 75° |
| July | 86° | 66° | 4.8" | 0.0" | 9 | 0 | 72° – 80° |
| August | 84° | 64° | 4.5" | 0.0" | 9 | 0 | 70° – 78° |
| September | 78° | 57° | 4.5" | 0.0" | 8 | 0 | 64° – 71° |
| October | 66° | 45° | 4.1" | 0.0" | 9 | 0 | 51° – 62° |
| November | 55° | 36° | 3.4" | 0.2" | 8 | 0 | 40° – 50° |
| December | 45° | 29° | 4.3" | 1.6" | 10 | 1 | 29° – 49° |
| Year | 64° | 44° | 48.3" | 7.6" | 111 | 9 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 29° to 49°. June is the most reliable, staying within 7°.
Where Roslyn’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 Roslyn’s center.
- Snow: Conshohocken, PA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Willow Grove Nas, PA, 5 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 Roslyn’s climate
What is the weather like in Roslyn?
A typical July afternoon reaches 86°, a January night drops to 24°, and about 8 inches of snow falls in a normal winter. Milder January nights than 59% of U.S. towns; hotter July afternoons than 58% of U.S. towns.
How cold does it get in Roslyn in winter?
January nights average 24°. About 92 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 24°.
How much snow does Roslyn get?
About 7.6 inches in a normal winter at Conshohocken, PA, most of it in January, with snow on the ground about 9 days a year.
How hot does it get in Roslyn?
July, with a typical high of 86° and a low of 66°. About 22 days a year reach 90° (Willow Grove Nas, PA).
When is the first and last frost in Roslyn?
In half of years the last spring frost (32°) comes by April 11 and the first fall frost by November 1, about 205 frost-free days, at Willow Grove Nas, PA.
What growing zone is Roslyn in?
Zone 7b 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 Roslyn?
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 Roslyn getting warmer?
Yes: 1991–2020 averaged 2.2° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 95% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Roslyn.
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.