Frost Dates for 64505 — Saint Joseph, Missouri

Half of springs at St Joseph Rosecrans Airport, MO see their last 32°F night by April 19; only one in ten is past it by April 5, and one in ten still has one after May 3. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 29 20%, and after May 3 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 80% of the 158 Missouri stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 17 in half of years, as early as September 30 one year in ten, and holds off past October 30 one year in ten. A hard freeze of 28°F follows 9 days later, around October 26; in spring the one-in-ten date for 28°F is April 24, 9 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, shorter than at 89% of the 158 Missouri stations; it reaches 201 days one year in ten and falls short of 159 one year in ten. On average 126 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 10 days longer, to about April 29, and return around October 5. Severe cold of 16°F or below comes every winter, usually between November 25 and March 9.

July is the warmest month at St Joseph Rosecrans Airport, MO, averaging 88°F by day and 67°F at night; January is the coldest at 37°F and 17°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 16% of years.

Warmth for growing adds up to 3,861 growing degree days a year (base 50°F), fewer than at 72% of the 158 Missouri stations. 37% of them (1,441) have built up by the end of June, and July adds the most, 859. Precipitation totals 34.9 inches a year, most in May (4.9") and least in January (0.7"); May to September bring 61% of it.

The nearest other station, Cosby 2W, MO, 8 miles east of Saint Joseph, has a last frost 2 days earlier (April 17), a first frost 2 days later (October 19), a season 4 days longer.

The first measurable snow (0.1 inch or more) in Saint Joseph usually arrives around December 1, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Troy 3N, KS, 13.1 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 29 days after the last snow.

ZIP 64505 is 5 miles from St Joseph Rosecrans Airport, MO, which stands at 818 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 64506 (Saint Joseph). The 2023 USDA Plant Hardiness Zone Map lists ZIP 64505 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.