Frost Dates for 19952 — Harrington, Delaware

Half of springs at Greenwood 2NE, DE see their last 32°F night by April 11; only one in ten is past it by March 29, and one in ten still has one after April 28. Planting tender crops after April 18 leaves a 30% risk of a frost on them, after April 22 20%, and after April 28 10%. The 17 days between the even-odds date and the one-in-ten date is the widest of the 10 Delaware stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 30 in half of years, as early as October 14 one year in ten, and holds off past November 13 one year in ten. A hard freeze of 28°F follows 12 days later, around November 11; in spring the one-in-ten date for 28°F is April 11, 17 days before the 32°F one. The freeze-free season lasts 200 days in a typical year, shorter than at 90% of the 10 Delaware stations; it reaches 222 days one year in ten and falls short of 177 one year in ten. On average 96 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 15 days longer, to about April 26, and return around October 19. Severe cold of 16°F or below comes in 99% of winters, usually between December 26 and February 23.

July is the warmest month at Greenwood 2NE, DE, averaging 87°F by day and 67°F at night; January is the coldest at 44°F and 25°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 82% of years.

Warmth for growing adds up to 3,757 growing degree days a year (base 50°F), fewer than at 70% of the 10 Delaware stations. 34% of them (1,271) have built up by the end of June, and July adds the most, 828. Precipitation totals 46.3 inches a year, most in September (4.8") and least in February (2.9"); May to September bring 46% of it.

The nearest other station, Dover, DE, 17 miles north of Harrington, has a last frost 7 days earlier (April 4), a first frost 5 days later (November 4), a season 14 days longer.

The first measurable snow (0.1 inch or more) in Harrington usually arrives around December 28, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Greenwood 2NE, DE, 7.2 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 41 days after the last snow.

ZIP 19952 is 7 miles from Greenwood 2NE, DE, which stands at 45 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 10 other ZIP codes share the station; its figures are presented in full for 19973 (Seaford). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19952 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.