Frost dates for St. Louis, Missouri
In St. Louis, half of springs have had their last frost by April 8 (and 1 spring in 10 still has one after April 23), and half of falls have had their first frost by October 26, leaving about 200 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
St. Louis, Missouri
Last spring frost
April 8
Half of springs have their last frost by this date. For a safer bet, wait until April 23: only 1 spring in 10 has a frost after that.
First fall frost
October 26
Half of falls have their first frost by this date. In 1 fall in 10 it comes by October 12.
Growing season
200 days
Frost-free days in a typical year. 9 years in 10 get at least 180.
Hardiness zone
7a
2023 USDA map: the coldest night of winter averages 0°F to 5°F. On the 2012 map it was 6b, half a zone colder. All 30 ZIP codes within about 6 miles of the city's center are in zone 7a.
Print a year planner for St. Louis
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | March 23 | April 8 | April 23 |
| First frost in fall | October 12 | October 26 | November 7 |
The frost-free season between them runs 200 days in a typical year. In 1 year in 10 it is 221 days or longer, and in 1 year in 10 it is 180 days or shorter.
- Hard freeze (28°F): typically last on March 28 and first on November 6. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on April 19 and first on October 17. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in St. Louis comes between March 23 and April 23, a window of 31 days. That is about average for NOAA's stations (the typical window is 31 days).
Among Missouri's 171 NOAA stations with a frost every year, 70 percent have their typical last frost later than St. Louis does.
Planting calendar for St. Louis
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
| When | What to do | Why then |
|---|---|---|
| January | ||
| January 21 to February 18 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
| February | ||
| February 4 to March 4 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| February 18 to March 11 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| February 25 to March 11 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| March | ||
| March 4 to 18 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| March 11 to 25 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March 11 to 25 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March 25 to April 8 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| March 25 to April 8 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| April | ||
| April 8 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| April 22 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| April 22 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| May | ||
| May 31 to June 14 | Cabbage for fall Start seeds | set the plants out by July 19 |
| June | ||
| June 20 to July 4 | Broccoli for fall Start seeds | set the plants out by August 8 |
| July | ||
| July 30 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August | ||
| August 3 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| August 4 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 8 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| August 9 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 13 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| August 23 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| September | ||
| September 2 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| September 12 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| October | ||
| October 12 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
| November | ||
| November 13 to 20 | Garlic Plant cloves | one or two weeks after the typical first hard freeze (28°F), our reading of the first killing frost |
Want more insurance? Shift every spring date 15 days later. That plans around April 23, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station Cahokia St Louis Airport (station USW00003960), 6 miles from the center of St. Louis. It sits at about the same elevation, 410 feet above sea level. NOAA rates this station's record as representative: at least 10 of the 30 years, with the gaps filled from nearby stations.
The same station also gives the frost dates for Arnold.
Our ZIP code lookup matches these 18 ZIP codes to the same station, so they get the same dates: 62040, 62059, 62060, 62090, 62201, 62203, 62204, 62205, 62206, 62207, 62208, 62223, 62232, 62234, 62239, 62240, 62260, 63102. Hardiness zones are worked out separately for each ZIP code.
The nearest other places with pages
- Springfield, Illinois: last frost around April 14, first frost around October 20 (85 miles away)
- Columbia, Missouri: last frost around April 5, first frost around October 31 (115 miles away)
- Peoria, Illinois: last frost around April 16, first frost around October 23 (150 miles away)
See frost dates across Missouri, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.