Frost Dates for 20186 — Warrenton, Virginia

Half of springs at Warrenton 3 SE, VA see their last 32°F night by April 9; only one in ten is past it by March 26, and one in ten still has one after April 28. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 20 20%, and after April 28 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 70% of the 128 Virginia stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 1 in half of years, as early as October 18 one year in ten, and holds off past November 14 one year in ten. A hard freeze of 28°F follows 13 days later, around November 14; 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 205 days in a typical year, longer than at 66% of the 128 Virginia stations; it reaches 226 days one year in ten and falls short of 184 one year in ten. On average 98 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 13 days longer, to about April 22, and return around October 21. Severe cold of 16°F or below comes every winter, usually between December 24 and February 25.

July is the warmest month at Warrenton 3 SE, VA, averaging 85°F by day and 66°F at night; January is the coldest at 42°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 78% of years.

Warmth for growing adds up to 3,630 growing degree days a year (base 50°F), fewer than at 59% of the 128 Virginia stations. 35% of them (1,269) have built up by the end of June, and July adds the most, 786.

The nearest other station, Manassas, VA, 17 miles east of Warrenton and 255 feet lower, has a last frost 3 days later (April 12), a first frost 5 days earlier (October 27), a season 8 days shorter.

The first measurable snow (0.1 inch or more) in Warrenton usually arrives around December 21, and the last of the season around March 3. Those are the middle dates across the winters of 1991–2020 at Warrenton 3 SE, VA, 3.1 miles away: half of years saw snow earlier, half later. Snow fell in 94% of those winters. The last 32°F night of spring typically comes 37 days after the last snow.

ZIP 20186 is 3 miles from Warrenton 3 SE, VA, which stands at 500 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 20187 (Warrenton). The 2023 USDA Plant Hardiness Zone Map lists ZIP 20186 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.