Frost Dates for 19541 — Mohrsville, Pennsylvania

Half of springs at Hamburg, PA see their last 32°F night by April 16; only one in ten is past it by April 2, and one in ten still has one after May 3. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 26 20%, and after May 3 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 50% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 25 in half of years, as early as October 9 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 9 days later, around November 3; in spring the one-in-ten date for 28°F is April 17, 16 days before the 32°F one. The freeze-free season lasts 189 days in a typical year, longer than at 78% of the 176 Pennsylvania stations; it reaches 209 days one year in ten and falls short of 167 one year in ten. On average 121 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 14 days longer, to about April 30, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 15 and March 3.

July is the warmest month at Hamburg, PA, averaging 85°F by day and 64°F at night; January is the coldest at 38°F and 20°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 14% of years.

Warmth for growing adds up to 3,237 growing degree days a year (base 50°F), more than at 76% of the 176 Pennsylvania stations. 34% of them (1,111) have built up by the end of June, and July adds the most, 770. Precipitation totals 49.6 inches a year, most in July (5.2") and least in February (2.7"); May to September bring 49% of it.

The nearest other station, Reading 4 NNW, PA, 6 miles southeast of Mohrsville, has a last frost 6 days earlier (April 10), a first frost 6 days later (October 31), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Mohrsville usually arrives around December 11, and the last of the season around March 13. Those are the middle dates across the winters of 1991–2020 at Hamburg, PA, 5.3 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 34 days after the last snow.

ZIP 19541 is 5 miles from Hamburg, PA, which stands at 369 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 19526 (Hamburg). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19541 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.