Frost dates for St. Charles 7 SSW, MO
At St. Charles 7 SSW, the median last spring frost (32°F) is Apr 4 and the median first fall frost is Oct 29, for a typical growing season of 206 days. For a 90% chance that the last frost has passed, wait until Apr 21. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- Apr 4Last spring frost (median)50% chance of 32°F after this date
- Apr 21Safer planting date10% chance of 32°F after this date
- Oct 29First fall frost (median)50% chance of 32°F by this date
- 206 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 3 | Apr 16 | May 1 |
| 32°F | Mar 20 | Apr 4 | Apr 21 |
| 28°F | Mar 8 | Mar 25 | Apr 8 |
| 24°F | Feb 27 | Mar 14 | Mar 30 |
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 | Oct 5 | Oct 19 | Oct 31 |
| 32°F | Oct 15 | Oct 29 | Nov 11 |
| 28°F | Oct 27 | Nov 8 | Nov 27 |
| 24°F | Nov 4 | Nov 20 | Dec 7 |
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 | 165 days | 185 days | 202 days |
| 32°F | 186 days | 206 days | 228 days |
| 28°F | 207 days | 228 days | 252 days |
| 24°F | 227 days | 249 days | 274 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 |
|---|---|---|---|
| 63017 | 7a | 0 to 5°F | 4 km |
| 63146 | 7a | 0 to 5°F | 4 km |
| 63141 | 7a | 0 to 5°F | 7 km |
| 63011 | 7a | 0 to 5°F | 9 km |
| 63131 | 7a | 0 to 5°F | 11 km |
| 63021 | 7a | 0 to 5°F | 13 km |
| 63088 | 6b | -5 to 0°F | 15 km |
| 63026 | 7a | 0 to 5°F | 21 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 USC00237398, at 38.6853, -90.5233, elevation 137 m (450 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 106.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- St. Peters 2 SE (11 km)
- St. Louis Sprt Of S L Airport (12 km)
- Weldon Spring NWS (14 km)
- St. Charles Elm Point (14 km)
- St. Louis Lambert Intl Airport (15 km)
- St. Louis Sci Center (23 km)
- St. Charles Co Airport (28 km)
- Washington (42 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.