Frost dates for Shelbyville Dam, IL
At Shelbyville Dam, the median last spring frost (32°F) is Apr 10 and the median first fall frost is Oct 24, for a typical growing season of 195 days. For a 90% chance that the last frost has passed, wait until Apr 28. Nearby ZIP codes are in USDA hardiness zones 6a to 6b.
- Apr 10Last spring frost (median)50% chance of 32°F after this date
- Apr 28Safer planting date10% chance of 32°F after this date
- Oct 24First fall frost (median)50% chance of 32°F by this date
- 195 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 9 | Apr 22 | May 9 |
| 32°F | Mar 30 | Apr 10 | Apr 28 |
| 28°F | Mar 15 | Mar 31 | Apr 14 |
| 24°F | Mar 4 | Mar 21 | Apr 4 |
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 27 |
| 32°F | Oct 8 | Oct 24 | Nov 5 |
| 28°F | Oct 20 | Nov 3 | Nov 21 |
| 24°F | Nov 1 | Nov 15 | Dec 4 |
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 | 153 days | 173 days | 192 days |
| 32°F | 175 days | 195 days | 214 days |
| 28°F | 197 days | 217 days | 238 days |
| 24°F | 217 days | 238 days | 263 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 |
|---|---|---|---|
| 62565 | 6a | -10 to -5°F | 3 km |
| 62438 | 6b | -5 to 0°F | 12 km |
| 62534 | 6a | -10 to -5°F | 14 km |
| 62444 | 6b | -5 to 0°F | 15 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 USC00117876, at 39.4078, -88.7739, elevation 198 m (650 ft).
- Data quality: Representative (10+ years), 24 years of freeze data.
- Average days per year at or below 32°F: 114.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Windsor (16 km)
- Sullivan 3s (22 km)
- Neoga 4nw (24 km)
- Pana (27 km)
- Effingham 3sw (35 km)
- Mattoon (37 km)
- Ramsey (40 km)
- Mattoon Coles Co Airport (43 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.