Frost Dates for 15904 — Johnstown, Pennsylvania

Half of springs at Johnstown Cambria Co Airport, PA see their last 32°F night by April 29; only one in ten is past it by April 14, and one in ten still has one after May 17. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 10 20%, and after May 17 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 21 in half of years, as early as October 5 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 12 days later, around November 2; in spring the one-in-ten date for 28°F is May 5, 12 days before the 32°F one. The freeze-free season lasts 176 days in a typical year, longer than at 52% of the 176 Pennsylvania stations; it reaches 197 days one year in ten and falls short of 153 one year in ten. On average 127 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 9 days longer, to about May 8, and return around October 8. Severe cold of 16°F or below comes every winter, usually between December 3 and March 16.

July is the warmest month at Johnstown Cambria Co Airport, PA, averaging 79°F by day and 61°F at night; January is the coldest at 33°F and 19°F. A freezing night is all but certain in every month from November 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 43% of years.

Warmth for growing adds up to 2,605 growing degree days a year (base 50°F), fewer than at 72% of the 176 Pennsylvania stations. 34% of them (898) have built up by the end of June, and July adds the most, 617. Precipitation totals 41.2 inches a year, most in June (4.4") and least in January (2.5"); May to September bring 50% of it.

The nearest other station, Ebensburg Sewage Plt, PA, 14 miles northeast of Johnstown and 344 feet lower, has a last frost 18 days later (May 17), a first frost 19 days earlier (October 2), a season 40 days shorter.

The first measurable snow (0.1 inch or more) in Johnstown usually arrives around November 5, and the last of the season around April 6. Those are the middle dates across the winters of 1991–2020 at Dunlo, PA, 7.5 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 23 days after the last snow.

ZIP 15904 is 3 miles from Johnstown Cambria Co Airport, PA, which stands at 2,284 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 12 other ZIP codes share the station; its figures are presented in full for 15905 (Johnstown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 15904 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.