Frost Dates for 29420 — North Charleston, South Carolina

Half of springs at Charleston International Airport, SC see their last 32°F night by March 7; only one in ten is past it by February 12, and one in ten still has one after March 27. Planting tender crops after March 15 leaves a 30% risk of a frost on them, after March 20 20%, and after March 27 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 91% of the 105 South Carolina stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 27 in half of years, as early as November 8 one year in ten, and holds off past December 21 one year in ten. A hard freeze of 28°F follows 18 days later, around December 15; in spring the one-in-ten date for 28°F is March 14, 13 days before the 32°F one. The freeze-free season lasts 266 days in a typical year, longer than at 92% of the 105 South Carolina stations; it reaches 298 days one year in ten and falls short of 238 one year in ten. On average 22 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 March 21, and return around November 13. Nights of 24°F, cold enough to damage hardier plants, come in 87% of winters and 16°F in 14%.

July is the warmest month at Charleston International Airport, SC, averaging 91°F by day and 74°F at night; January is the coldest at 60°F and 39°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 90% of years and March still brings one in 64% of years.

Warmth for growing adds up to 6,385 growing degree days a year (base 50°F), more than at 92% of the 105 South Carolina stations. 41% of them (2,625) have built up by the end of June, and July adds the most, 1,007. Precipitation totals 52.7 inches a year, most in August (7.0") and least in November (2.7"); May to September bring 55% of it.

The nearest other station, Summerville 4W, SC, 11 miles northwest of North Charleston, has a last frost 15 days later (March 22), a first frost 15 days earlier (November 12), a season 28 days shorter.

Measurable snow is rare here: only 4 of 30 winters from 1991 to 2020 recorded 0.1 inch or more at Charleston International Airport, SC, 3.7 miles away, so there is no typical first-snow date to plan around.

ZIP 29420 is 4 miles from Charleston International Airport, SC, which stands at 40 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 9 other ZIP codes share the station; its figures are presented in full for 29445 (Goose Creek). The 2023 USDA Plant Hardiness Zone Map lists ZIP 29420 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.