Frost Dates for 30009 — Alpharetta, Georgia

Half of springs at Atlanta Fulton Co Airport, GA see their last 32°F night by March 24; only one in ten is past it by March 2, and one in ten still has one after April 10. Planting tender crops after March 31 leaves a 30% risk of a frost on them, after April 4 20%, and after April 10 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 56% of the 127 Georgia stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 8 in half of years, as early as October 27 one year in ten, and holds off past November 26 one year in ten. A hard freeze of 28°F follows 12 days later, around November 20; in spring the one-in-ten date for 28°F is March 27, 14 days before the 32°F one. The freeze-free season lasts 231 days in a typical year, shorter than at 58% of the 127 Georgia stations; it reaches 258 days one year in ten and falls short of 207 one year in ten. On average 52 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 April 7, and return around October 29. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 65%.

July is the warmest month at Atlanta Fulton Co Airport, GA, averaging 90°F by day and 70°F at night; January is the coldest at 54°F and 34°F. A freezing night is all but certain in every month from November to February (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 88% of years and April still brings one in 29% of years.

Warmth for growing adds up to 5,219 growing degree days a year (base 50°F), fewer than at 60% of the 127 Georgia stations. 40% of them (2,075) have built up by the end of June, and July adds the most, 933. Precipitation totals 48.1 inches a year, most in July (5.0") and least in September (3.4"); May to September bring 41% of it.

The nearest other station, Mableton 1 N, GA, 6 miles west of Alpharetta, has a last frost 3 days later (March 27), a first frost 1 day earlier (November 7), a season 6 days shorter.

Measurable snow is rare here: only 4 of 23 winters from 1991 to 2020 recorded 0.1 inch or more at Atlanta 9NW, GA, 1.8 miles away, so there is no typical first-snow date to plan around.

ZIP 30009 is 5 miles from Atlanta Fulton Co Airport, GA, which stands at 840 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 12 other ZIP codes share the station; its figures are presented in full for 30135 (Douglasville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 30009 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°C) over 1991–2020; a zone describes winter lows, not frost dates.