Frost dates / Missouri / Florissant

Frost dates in Florissant, MO

The station on this page is ST LOUIS LAMBERT INTL AP, MO US (USW00013994), 4.1 miles from the city point. Population in the Census 2024 estimate is 51,290.

Zone 7aUSDA average annual extreme minimum 0°F to 5°F, from ZIP 63031 (1.7 miles from the city point used on this page).

Median last 32°F is April 2. Median first 32°F is November 4. The 50% growing-season length is 215 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	March 17	Earlier date. A last 32°F on or after this day is common.
50%	April 2	Median.
10%	April 17	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	October 23	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 4	Median.
90%	November 18	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	236
50%	215
90%	196

28°F threshold

	10%	50%	90%
Last, on or after	April 7	March 23	March 5
First, on or before	November 2	November 13	November 30
Season at least	258 days	236 days	216 days

36°F threshold

	10%	50%	90%
Last, on or after	April 28	April 13	March 31
First, on or before	October 14	October 26	November 6
Season at least	213 days	195 days	176 days

Station ST LOUIS LAMBERT INTL AP, MO US (USW00013994). Completeness flag S, 30 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 161.8 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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Florissant, MO

Zone 7aAverage annual extreme minimum 0°F to 5°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Missouri. Nearest qualified station: ST LOUIS LAMBERT INTL AP, MO US (USW00013994), 4.1 miles. Median last 32°F April 2. Median first 32°F November 4. The 50% growing-season length is 215 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 17	April 2	March 17
First 32°F on or before	October 23	November 4	November 18

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

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Planting calendar

Frost dates for Missouri are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

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