Frost Dates for 20141 — Round Hill, Virginia

Half of springs at Purcellville, VA see their last 32°F night by April 16; only one in ten is past it by March 31, and one in ten still has one after May 7. Planting tender crops after April 24 leaves a 30% risk of a frost on them, after April 30 20%, and after May 7 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 92% of the 128 Virginia stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by October 25 in half of years, as early as October 7 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 11 days later, around November 5; in spring the one-in-ten date for 28°F is April 17, 20 days before the 32°F one. The freeze-free season lasts 189 days in a typical year, shorter than at 61% of the 128 Virginia stations; it reaches 210 days one year in ten and falls short of 165 one year in ten. On average 115 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 May 1, and return around October 12. Severe cold of 16°F or below comes every winter, usually between December 18 and February 26.

July is the warmest month at Purcellville, VA, averaging 86°F by day and 66°F at night; January is the coldest at 41°F and 25°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 87% of years and May still brings one in 18% of years.

Warmth for growing adds up to 3,557 growing degree days a year (base 50°F), fewer than at 65% of the 128 Virginia stations. 35% of them (1,235) have built up by the end of June, and July adds the most, 804. Precipitation totals 44.0 inches a year, most in September (4.8") and least in February (2.6"); May to September bring 48% of it.

The nearest other station, Mt Wx, VA, 7 miles southwest of Round Hill and 1,149 feet higher, has a last frost 1 day later (April 17), a first frost 7 days later (November 1), a season 9 days longer.

The first measurable snow (0.1 inch or more) in Round Hill usually arrives around January 8, and the last of the season around February 18. Those are the middle dates across the winters of 1991–2020 at Purcellville, VA, 3.8 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 57 days after the last snow.

ZIP 20141 is 4 miles from Purcellville, VA, which stands at 510 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 20176 (Leesburg). The 2023 USDA Plant Hardiness Zone Map lists ZIP 20141 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.