St. Louis, MO Frost Dates: Last Spring and First Fall Frost

Frost leaves St. Louis on April 1 and comes back on November 4 when the odds are even, a window of 218 days for tender plants.

Dates at even odds leave half of all years unprotected. The safer pair for St. Louis is April 18 in spring, which only one year in ten passes, and October 24 in fall, which one year in ten arrives before. The 100 cities covered here have a median season of 229 days, and St. Louis is close to it.

NOAA measured them at St Louis Science Center (station USC00237452), about 1.5 miles west of the Census Bureau's internal point for St. Louis and about 520 feet above sea level.

Last spring frost in St. Louis

Frost is still possible on March 14 in nine springs out of ten and on April 1 in five; only one spring in ten sees a freeze as late as April 18.

The early and late dates are 35 days apart, about the spread most cities on these pages show.

St. Louis's first fall frost, by chance

A first freeze on or before October 24 happens one fall in ten. By November 4 half of years have had one, and by November 21 nine years in ten have.

Fall frost keeps to a tight calendar in St. Louis: 28 days from the 10% date to the 90% date, less than in most of the 100 cities here.

St. Louis's frost-free season

Neither long nor short next to the other cities here. Seasons here barely vary: the typical year gives 218 days and a short one still gives 198 days, only 20 days less, a steadier record than most cities on these pages.

The season lengths come from NOAA's simulated years, not from subtracting one typical date from the other, so the two will not match to the day. A night at or below 32°F happens in 100% of years at this station, so frost is a yearly event here.

28°F dates in St. Louis

Between a light frost and a hard freeze there is little room in St. Louis: the typical 28°F dates are November 15 and March 22, just 11 days and 10 days from the 32°F dates. The late 28°F spring date, April 7, is the one that still catches blooms and young transplants one year in ten, and the early fall date, November 2, is when a hard freeze has arrived in one fall out of ten.

Using St. Louis's frost dates in the garden

The University of New Hampshire Extension sheet times each crop from the last frost. For St. Louis's typical date, April 1, that means cabbage on March 4, lettuce from March 4 to March 11, seed potatoes from March 18 to March 25, and, once the frost is behind you, peppers on April 15 and beans on or after April 1. The University of New Hampshire Extension sheet gives peas no frost count at all; sow them as soon as the soil thaws.

The late date comes 17 days after the typical one; choose it for plants you cannot cover.

Fall crops are counted back from the first frost, using NC State Extension's days to harvest plus University of Georgia Extension's harvest allowance of 18 days. In St. Louis only 32 of the 34 crops in the fall planner have a last planting day in July or later, and the other 2 would have to go in before then, in spring or early summer. The slowest crop that still fits is lima/pole beans, at 113 days, and it has to be planted by July 3 to beat the early date.

Worked example: a tomato plan for St. Louis

Take tomatoes in St. Louis. The University of New Hampshire Extension rule is to set transplants out one to two weeks after the last frost. From April 1, the typical date, that means April 8 to April 15; from April 18, the late date, it means April 25 to May 2, a delay of 17 days.

Indoors, tomato seeds go in six to eight weeks ahead of set-out; from the first day of the late window that is February 28 to March 14.

From the last set-out day to the early first frost on October 24 is 175 days. NC State Extension gives 75 to 85 days, and the longer figure still fits with 90 days to spare.

About the St Louis Science Center station

At 1.5 miles west of the city's internal point, the station is very close to St. Louis.

At about 520 feet, it ranks above 37 and below 62 of the 100 stations used for these pages. NOAA flags this station's record as representative, the code R, for the data behind its 50% last-frost value.

No elevation is available for St. Louis in the Census data we saved, so the station's height may or may not match your garden's. Compare nearby stations in the frost dates tool if it does not, and err toward the colder dates.

Nearby cities and their frost dates

The closest city to St. Louis on these pages, Indianapolis, IN, is 233 miles away, a long way, so the three below are a look at other climates more than at neighbors.

• Indianapolis, IN (233 miles, east): spring frost lingers 19 days longer than in St. Louis, and the season runs 35 days shorter. Its typical dates are April 20 and October 21, with 183 days frost-free.
• Kansas City, MO, 234 miles to the west: last frost April 4, first frost November 2, 211 days frost-free; spring frost ends about when it does in St. Louis, and the season is within about a week of St. Louis's.
• Overland Park, KS (240 miles, west): the last frost is 9 days later than in St. Louis, and it has 16 days less without frost. Its typical dates are April 10 and October 29, with 202 days frost-free.

Next steps for St. Louis gardeners

To go beyond the crops above, use the spring planting planner and fall planting planner, both set to this station. The frost dates tool shows the full odds for St. Louis, and the hardiness zone lookup gives the winter-cold zone for your ZIP code.

Looking for another city? The city frost dates index lists every page, grouped by state.

For Missouri, the state planting pages copy the Extension calendar (MU Extension, University of Missouri) crop by crop and region by region: tomatoes in Missouri, peppers in Missouri, cucumbers in Missouri, summer squash in Missouri, green beans in Missouri, potatoes in Missouri. Set those windows beside the frost dates above.

Where these numbers come from

The frost and freeze dates are NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11), copied from the station's own record without adjustment; NOAA's documentation defines each probability. The Census Bureau's 2024 Gazetteer places St. Louis on the map, and its Vintage 2024 estimates, 279,695 people here, decide which cities get a page.

The planting dates apply the count rules in University of New Hampshire Extension, NC State Extension and University of Georgia Extension to this station's dates, with nothing added. See how we source every figure for the checks behind them.

NOAA's dates say how often frost has come, not when it will. Check the forecast before planting and keep a cover on hand.