Frost Dates for 16662 — Martinsburg, Pennsylvania

Half of springs at Altoona Blair Co Airport, PA see their last 32°F night by April 23; only one in ten is past it by April 8, and one in ten still has one after May 11. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 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 4 one year in ten. A hard freeze of 28°F follows 11 days later, around November 1; in spring the one-in-ten date for 28°F is April 29, 12 days before the 32°F one. The freeze-free season lasts 177 days in a typical year, longer than at 56% of the 176 Pennsylvania stations; it reaches 200 days one year in ten and falls short of 154 one year in ten. On average 118 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 4, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 10 and March 10.

July is the warmest month at Altoona Blair Co Airport, PA, averaging 83°F by day and 62°F at night; January is the coldest at 36°F and 21°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 28% of years.

Warmth for growing adds up to 2,977 growing degree days a year (base 50°F), more than at 50% of the 176 Pennsylvania stations. 35% of them (1,039) have built up by the end of June, and July adds the most, 693. Precipitation totals 36.8 inches a year, most in September (4.0") and least in February (2.0"); May to September bring 49% of it.

The nearest other station, Altoona 7 SW, PA, 9 miles northwest of Martinsburg and 300 feet lower, has a last frost 2 days later (April 25), a first frost 1 day earlier (October 20).

The first measurable snow (0.1 inch or more) in Martinsburg usually arrives around November 18, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Altoona 7 SW, PA, 9.4 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 29 days after the last snow.

ZIP 16662 is under a mile from Altoona Blair Co Airport, PA, which stands at 1,480 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 16662 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.