Frost dates for Petersburg 1e, IL
At Petersburg 1e, the median last spring frost (32°F) is Apr 13 and the median first fall frost is Oct 21, for a typical growing season of 189 days. For a 90% chance that the last frost has passed, wait until Apr 28. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 13Last spring frost (median)50% chance of 32°F after this date
- Apr 28Safer planting date10% chance of 32°F after this date
- Oct 21First fall frost (median)50% chance of 32°F by this date
- 189 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 8 |
| 32°F | Mar 31 | Apr 13 | Apr 28 |
| 28°F | Mar 18 | Apr 3 | Apr 17 |
| 24°F | Mar 9 | Mar 24 | Apr 7 |
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 23 |
| 32°F | Oct 7 | Oct 21 | Nov 3 |
| 28°F | Oct 19 | Nov 1 | Nov 14 |
| 24°F | Oct 28 | Nov 11 | Nov 28 |
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 | 150 days | 169 days | 187 days |
| 32°F | 170 days | 189 days | 209 days |
| 28°F | 190 days | 210 days | 233 days |
| 24°F | 210 days | 231 days | 255 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 |
|---|---|---|---|
| 62675 | 6a | -10 to -5°F | 3 km |
| 62688 | 6a | -10 to -5°F | 11 km |
| 62673 | 6a | -10 to -5°F | 15 km |
| 62627 | 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 USC00116765, at 40.0164, -89.8344, elevation 183 m (600 ft).
- Data quality: Estimated from nearby stations (2+ years), 5 years of freeze data.
- Average days per year at or below 32°F: 121.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Athens 4sw (10 km)
- Mason City 4se (23 km)
- Springfield Capital Airport (23 km)
- Springfield #2 (28 km)
- Havana (37 km)
- Jacksonville 2e (44 km)
- Lincoln (45 km)
- Jacksonville 2 (48 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.