Frost Dates for 63116 — Saint Louis, Missouri

Half of springs at St Louis Sci Ctr, MO see their last 32°F night by April 1; only one in ten is past it by March 14, and one in ten still has one after April 18. Planting tender crops after April 7 leaves a 30% risk of a frost on them, after April 11 20%, and after April 18 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 66% of the 158 Missouri stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 4 in half of years, as early as October 24 one year in ten, and holds off past November 21 one year in ten. A hard freeze of 28°F follows 11 days later, around November 15; in spring the one-in-ten date for 28°F is April 7, 11 days before the 32°F one. The freeze-free season lasts 218 days in a typical year, longer than at 96% of the 158 Missouri stations; it reaches 240 days one year in ten and falls short of 198 one year in ten. On average 79 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 11 days longer, to about April 12, and return around October 26. Severe cold of 16°F or below comes every winter, usually between December 19 and February 23.

July is the warmest month at St Louis Sci Ctr, MO, averaging 90°F by day and 72°F at night; January is the coldest at 41°F and 25°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 52% of years.

Warmth for growing adds up to 4,703 growing degree days a year (base 50°F), more than at 96% of the 158 Missouri stations. 38% of them (1,768) have built up by the end of June, and July adds the most, 949. Precipitation totals 43.9 inches a year, most in May (4.9") and least in February (2.3"); May to September bring 48% of it.

The nearest other station, Cahokia, IL, 4 miles east of Saint Louis, has a last frost 5 days later (April 6), a first frost 8 days earlier (October 27), a season 15 days shorter.

The first measurable snow (0.1 inch or more) in Saint Louis usually arrives around December 25, and the last of the season around February 27. Those are the middle dates across the winters of 1991–2020 at St Louis Sci Ctr, MO, 3.5 miles away: half of years saw snow earlier, half later. Snow fell in 97% of those winters. The last 32°F night of spring typically comes 33 days after the last snow.

ZIP 63116 is 4 miles from St Louis Sci Ctr, MO, which stands at 515 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 28 other ZIP codes share the station; its figures are presented in full for 63123 (Saint Louis). The 2023 USDA Plant Hardiness Zone Map lists ZIP 63116 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.