Frost dates for Weldon Spring NWS, MO
At Weldon Spring NWS, the median last spring frost (32°F) is Apr 10 and the median first fall frost is Oct 26, for a typical growing season of 199 days. For a 90% chance that the last frost has passed, wait until Apr 26. Nearby ZIP codes are in USDA hardiness zone 6b.
- Apr 10Last spring frost (median)50% chance of 32°F after this date
- Apr 26Safer planting date10% chance of 32°F after this date
- Oct 26First fall frost (median)50% chance of 32°F by this date
- 199 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 8 | Apr 22 | May 6 |
| 32°F | Mar 26 | Apr 10 | Apr 26 |
| 28°F | Mar 12 | Mar 31 | Apr 15 |
| 24°F | Mar 2 | Mar 19 | Apr 3 |
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 1 | Oct 16 | Oct 28 |
| 32°F | Oct 12 | Oct 26 | Nov 8 |
| 28°F | Oct 22 | Nov 5 | Nov 22 |
| 24°F | Nov 2 | Nov 17 | Dec 3 |
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 | 155 days | 176 days | 196 days |
| 32°F | 178 days | 199 days | 220 days |
| 28°F | 199 days | 221 days | 242 days |
| 24°F | 221 days | 243 days | 267 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 |
|---|---|---|---|
| 63304 | 6b | -5 to 0°F | 1 km |
| 63368 | 6b | -5 to 0°F | 7 km |
| 63341 | 6b | -5 to 0°F | 12 km |
| 63367 | 6b | -5 to 0°F | 13 km |
| 63365 | 6b | -5 to 0°F | 17 km |
| 63385 | 6b | -5 to 0°F | 19 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 USC00238805, at 38.6989, -90.6828, elevation 186 m (610 ft).
- Data quality: Standard (24+ years of data), 29 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
- St. Louis Sprt Of S L Airport (5 km)
- St. Peters 2 SE (11 km)
- St. Charles 7 SSW (14 km)
- St. Charles Elm Point (19 km)
- St. Louis Lambert Intl Airport (27 km)
- Washington (31 km)
- St. Charles Co Airport (34 km)
- St. Louis Sci Center (37 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.