Frost dates / Missouri / St. Louis

Frost dates in St. Louis, MO

The station on this page is ST LOUIS SCI CTR, MO US (USC00237452), 1.5 miles from the city point. Population in the Census 2024 estimate is 279,695.

Zone 7aUSDA average annual extreme minimum 0°F to 5°F, from ZIP 63108 (0.8 miles from the city point used on this page).

Median last 32°F is April 1. Median first 32°F is November 4. The 50% growing-season length is 218 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 14	Earlier date. A last 32°F on or after this day is common.
50%	April 1	Median.
10%	April 18	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 24	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 4	Median.
90%	November 21	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%	240
50%	218
90%	198

28°F threshold

	10%	50%	90%
Last, on or after	April 7	March 22	March 5
First, on or before	November 2	November 15	December 4
Season at least	264 days	239 days	217 days

36°F threshold

	10%	50%	90%
Last, on or after	April 27	April 12	March 27
First, on or before	October 15	October 26	November 7
Season at least	216 days	197 days	178 days

Station ST LOUIS SCI CTR, MO US (USC00237452). Completeness flag R, 25 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 157 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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St. Louis, 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 SCI CTR, MO US (USC00237452), 1.5 miles. Median last 32°F April 1. Median first 32°F November 4. The 50% growing-season length is 218 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 18	April 1	March 14
First 32°F on or before	October 24	November 4	November 21

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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