Frost Dates for 63020 — De Soto, Missouri

Half of springs at Festus, MO see their last 32°F night by April 9; only one in ten is past it by March 25, and one in ten still has one after April 25. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 20 20%, and after April 25 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 35% of the 158 Missouri stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 26 in half of years, as early as October 14 one year in ten, and holds off past November 8 one year in ten. A hard freeze of 28°F follows 10 days later, around November 5; in spring the one-in-ten date for 28°F is April 15, 10 days before the 32°F one. The freeze-free season lasts 197 days in a typical year, longer than at 58% of the 158 Missouri stations; it reaches 220 days one year in ten and falls short of 177 one year in ten. On average 105 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 17. Severe cold of 16°F or below comes every winter, usually between December 9 and March 1.

July is the warmest month at Festus, MO, averaging 88°F by day and 67°F at night; January is the coldest at 41°F and 22°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 77% of years.

Warmth for growing adds up to 4,095 growing degree days a year (base 50°F), more than at 56% of the 158 Missouri stations. 37% of them (1,500) have built up by the end of June, and July adds the most, 862. Precipitation totals 43.5 inches a year, most in April (4.9") and least in February (2.5"); May to September bring 47% of it.

The nearest other station, Potosi 4 SW, MO, 22 miles southwest of De Soto and 505 feet higher, has a last frost 2 days later (April 11), a first frost 2 days later (October 28), a season 1 day longer.

The first measurable snow (0.1 inch or more) in De Soto usually arrives around December 21, and the last of the season around March 2. Those are the middle dates across the winters of 1991–2020 at Festus, MO, 11.5 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 38 days after the last snow.

ZIP 63020 is 12 miles from Festus, MO, which stands at 600 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 13 other ZIP codes share the station; its figures are presented in full for 63010 (Arnold). The 2023 USDA Plant Hardiness Zone Map lists ZIP 63020 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.