Frost Dates for 15424 — Confluence, Pennsylvania

Half of springs at Confluence 1 SW Dam, PA see their last 32°F night by April 30; only one in ten is past it by April 17, and one in ten still has one after May 18. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 11 20%, and after May 18 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 70% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 18 in half of years, as early as October 4 one year in ten, and holds off past October 31 one year in ten. A hard freeze of 28°F follows 11 days later, around October 29; in spring the one-in-ten date for 28°F is May 2, 16 days before the 32°F one. The freeze-free season lasts 171 days in a typical year, shorter than at 57% of the 176 Pennsylvania stations; it reaches 190 days one year in ten and falls short of 149 one year in ten. On average 148 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about May 11, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 1 and March 17.

July is the warmest month at Confluence 1 SW Dam, PA, averaging 84°F by day and 60°F at night; January is the coldest at 37°F and 19°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 44% of years.

Warmth for growing adds up to 2,870 growing degree days a year (base 50°F), fewer than at 58% of the 176 Pennsylvania stations. 34% of them (979) have built up by the end of June, and July adds the most, 670. Precipitation totals 47.2 inches a year, most in May (4.9") and least in November (3.1"); May to September bring 47% of it.

The nearest other station, Chalk Hill 2 ENE, PA, 13 miles west of Confluence and 490 feet higher, has a last frost 19 days later (May 19), a first frost 17 days earlier (October 1), a season 36 days shorter.

The first measurable snow (0.1 inch or more) in Confluence usually arrives around November 16, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Confluence 1 SW Dam, PA, 1.6 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 30 days after the last snow.

ZIP 15424 is 2 miles from Confluence 1 SW Dam, PA, which stands at 1,490 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 15424 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.