Frost dates in St. Louis, Missouri
NOAA 1991–2020 normals for a 32 °F freeze. Low spots and the edge of town run colder than downtown.
Short answer
The average last spring frost in St. Louis is April 8, and the average first fall frost is October 26, from NOAA's Cahokia St Louis Airport station, 6 miles from the middle of St. Louis. 1 year in 10 the last frost comes after April 23, and the first one by October 12. That leaves about 201 frost-free days. St. Louis is in USDA planting zone 7a.
Weather stations around St. Louis
The first row is the date most people in St. Louis go by. The others show how far the dates move across the area.
| Station | Last spring frost | First fall frost | Frost-free |
|---|---|---|---|
| Cahokia St Louis Airport 6 mi away, 413 ft | April 8 1 in 10 after April 23 | October 26 1 in 10 by October 12 | 201 days |
| St Louis Sci Ctr 1 mi away, 515 ft | April 1 1 in 10 after April 18 | November 4 1 in 10 by October 24 | 217 days |
| Cahokia 5 mi away, 400 ft | April 6 1 in 10 after April 20 | October 27 1 in 10 by October 14 | 204 days |
| St Louis Lambert Intl Airport 11 mi away, 531 ft | April 2 1 in 10 after April 17 | November 4 1 in 10 by October 23 | 216 days |
| St Charles 7 SSW 15 mi away, 450 ft | April 4 1 in 10 after April 21 | October 29 1 in 10 by October 15 | 208 days |
Distances are from the middle of St. Louis as the Census Bureau maps it. The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. The planting zone is the USDA 2023 zone for ZIP code 63108, at the middle of the city.
Your exact ZIP code
St. Louis covers a lot of ground. For the station nearest your own street, and its planting zone, type your ZIP code.
How these dates work
Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.
The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.
More frost dates
All of Missouri, station by station.
Other Missouri cities: Kansas City · Springfield
Nearby: Clarksville, TN · Joliet, IL · Indianapolis, IN
Where the numbers come from
- USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture
- PRISM Climate Group, Oregon State University (zone data)
- NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal
- NOAA, Normals calculation methodology (frost-freeze probability dates)
- US Census Bureau, 2025 ZCTA gazetteer (ZIP code centers)
- US Census Bureau, 2025 city population estimates and place gazetteer