Frost Dates for 39666 — Summit, Mississippi

Half of springs at Mccomb/Pike Co/John E Lewis Airport, MS see their last 32°F night by March 11; only one in ten is past it by February 17, and one in ten still has one after April 2. Planting tender crops after March 20 leaves a 30% risk of a frost on them, after March 26 20%, and after April 2 10%. The 22 days between the even-odds date and the one-in-ten date is wider than at 85% of the 96 Mississippi 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 November 18 in half of years, as early as November 1 one year in ten, and holds off past December 7 one year in ten. A hard freeze of 28°F follows 13 days later, around December 1; in spring the one-in-ten date for 28°F is March 18, 15 days before the 32°F one. The freeze-free season lasts 253 days in a typical year, longer than at 80% of the 96 Mississippi stations; it reaches 282 days one year in ten and falls short of 225 one year in ten. On average 30 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 17 days longer, to about March 28, and return around November 7. Nights of 24°F, cold enough to damage hardier plants, come in 93% of winters and 16°F in 27%.

July is the warmest month at Mccomb/Pike Co/John E Lewis Airport, MS, averaging 91°F by day and 71°F at night; January is the coldest at 60°F and 38°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to October the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 70% of years and April still brings one in 12% of years.

Warmth for growing adds up to 6,290 growing degree days a year (base 50°F), more than at 80% of the 96 Mississippi stations. 42% of them (2,634) have built up by the end of June, and July adds the most, 963. Precipitation totals 60.6 inches a year, most in January (6.4") and least in October (3.8"); May to September bring 43% of it.

The nearest other station, Brookhaven City, MS, 17 miles north of Summit, has a last frost 6 days later (March 17), a first frost 6 days earlier (November 12), a season 11 days shorter.

Measurable snow is rare here: only 4 of 16 winters from 1991 to 2020 recorded 0.1 inch or more at Mccomb/Pike Co/John E Lewis Airport, MS, 7.6 miles away, so there is no typical first-snow date to plan around.

ZIP 39666 is 8 miles from Mccomb/Pike Co/John E Lewis Airport, MS, which stands at 413 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 39648 (Mccomb). The 2023 USDA Plant Hardiness Zone Map lists ZIP 39666 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.