Frost Dates for 21093 — Lutherville, Maryland

Half of springs at Cylburn, MD see their last 32°F night by April 2; only one in ten is past it by March 20, and one in ten still has one after April 13. Planting tender crops after April 6 leaves a 30% risk of a frost on them, after April 9 20%, and after April 13 10%. The 11 days between the even-odds date and the one-in-ten date is narrower than at 94% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 7 in half of years, as early as October 27 one year in ten, and holds off past November 21 one year in ten. A hard freeze of 28°F follows 13 days later, around November 20; in spring the one-in-ten date for 28°F is April 3, 10 days before the 32°F one. The freeze-free season lasts 220 days in a typical year, longer than at 78% of the 50 Maryland stations; it reaches 239 days one year in ten and falls short of 203 one year in ten. On average 92 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 12 days longer, to about April 14, and return around October 27. Severe cold of 16°F or below comes in 97% of winters, usually between January 3 and February 17.

July is the warmest month at Cylburn, MD, averaging 87°F by day and 69°F at night; January is the coldest at 42°F and 27°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 58% of years.

Warmth for growing adds up to 3,925 growing degree days a year (base 50°F), more than at 52% of the 50 Maryland stations. 35% of them (1,388) have built up by the end of June, and July adds the most, 865.

The nearest other station, Md Sci Ctr Baltimore, MD, 11 miles south of Lutherville and 215 feet lower, has a last frost 9 days earlier (March 24), a first frost 14 days later (November 21), a season 24 days longer.

The first measurable snow (0.1 inch or more) in Lutherville usually arrives around December 11, and the last of the season around March 11. Those are the middle dates across the winters of 1991–2020 at Baltimore Wash International Airport, MD, 18.8 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 22 days after the last snow.

ZIP 21093 is 6 miles from Cylburn, MD, which stands at 235 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 29 other ZIP codes share the station; its figures are presented in full for 21234 (Baltimore). The 2023 USDA Plant Hardiness Zone Map lists ZIP 21093 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.