Frost dates for St. Louis Sprt Of S L Airport, MO
At St. Louis Sprt Of S L Airport, the median last spring frost (32°F) is Apr 12 and the median first fall frost is Oct 23, for a typical growing season of 193 days. For a 90% chance that the last frost has passed, wait until Apr 27. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- Apr 12Last spring frost (median)50% chance of 32°F after this date
- Apr 27Safer planting date10% chance of 32°F after this date
- Oct 23First fall frost (median)50% chance of 32°F by this date
- 193 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 10 | Apr 24 | May 7 |
| 32°F | Mar 28 | Apr 12 | Apr 27 |
| 28°F | Mar 14 | Mar 31 | Apr 17 |
| 24°F | Mar 2 | Mar 20 | Apr 5 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 30 | Oct 14 | Oct 26 |
| 32°F | Oct 11 | Oct 23 | Nov 5 |
| 28°F | Oct 22 | Nov 3 | Nov 18 |
| 24°F | Nov 2 | Nov 14 | Dec 2 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 152 days | 171 days | 190 days |
| 32°F | 172 days | 193 days | 213 days |
| 28°F | 196 days | 216 days | 237 days |
| 24°F | 219 days | 240 days | 265 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 63005 | 6b | -5 to 0°F | 1 km |
| 63038 | 7a | 0 to 5°F | 9 km |
| 63040 | 7a | 0 to 5°F | 9 km |
| 63073 | 6b | -5 to 0°F | 13 km |
| 63025 | 6b | -5 to 0°F | 19 km |
| 63069 | 6b | -5 to 0°F | 22 km |
| 63049 | 7a | 0 to 5°F | 23 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USW00003966, at 38.6572, -90.6558, elevation 141 m (462 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 105.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Weldon Spring NWS (5 km)
- St. Charles 7 SSW (12 km)
- St. Peters 2 SE (14 km)
- St. Charles Elm Point (21 km)
- St. Louis Lambert Intl Airport (27 km)
- Washington (31 km)
- St. Louis Sci Center (34 km)
- St. Charles Co Airport (36 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.