Frost dates for Charleston, IL
At Charleston, the median last spring frost (32°F) is Apr 15 and the median first fall frost is Oct 23, for a typical growing season of 187 days. For a 90% chance that the last frost has passed, wait until May 3. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 15Last spring frost (median)50% chance of 32°F after this date
- May 3Safer planting date10% chance of 32°F after this date
- Oct 23First fall frost (median)50% chance of 32°F by this date
- 187 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 13 | Apr 27 | May 15 |
| 32°F | Apr 1 | Apr 15 | May 3 |
| 28°F | Mar 20 | Apr 3 | Apr 20 |
| 24°F | Mar 6 | Mar 25 | Apr 10 |
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 29 | Oct 12 | Oct 25 |
| 32°F | Oct 9 | Oct 23 | Nov 4 |
| 28°F | Oct 19 | Nov 2 | Nov 16 |
| 24°F | Nov 1 | Nov 13 | 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 | 143 days | 165 days | 185 days |
| 32°F | 163 days | 187 days | 209 days |
| 28°F | 190 days | 213 days | 235 days |
| 24°F | 214 days | 236 days | 260 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 |
|---|---|---|---|
| 61920 | 6a | -10 to -5°F | 4 km |
| 62474 | 6a | -10 to -5°F | 11 km |
| 61912 | 6a | -10 to -5°F | 12 km |
| 61943 | 6a | -10 to -5°F | 24 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 USC00111436, at 39.4761, -88.1653, elevation 213 m (700 ft).
- Data quality: Standard (24+ years of data), 27 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
- Mattoon Coles Co Airport (10 km)
- Mattoon (16 km)
- Casey (26 km)
- Neoga 4nw (32 km)
- Tuscola (37 km)
- Windsor (37 km)
- Sullivan 3s (39 km)
- Paris Stp (46 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.