Frost dates for Park Forest, IL
At Park Forest, the median last spring frost (32°F) is Apr 23 and the median first fall frost is Oct 20, for a typical growing season of 179 days. For a 90% chance that the last frost has passed, wait until May 11. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 23Last spring frost (median)50% chance of 32°F after this date
- May 11Safer planting date10% chance of 32°F after this date
- Oct 20First fall frost (median)50% chance of 32°F by this date
- 179 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 20 | May 5 | May 24 |
| 32°F | Apr 9 | Apr 23 | May 11 |
| 28°F | Mar 30 | Apr 12 | Apr 27 |
| 24°F | Mar 15 | Apr 1 | Apr 17 |
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 27 | Oct 10 | Oct 22 |
| 32°F | Oct 6 | Oct 20 | Nov 1 |
| 28°F | Oct 18 | Oct 30 | Nov 15 |
| 24°F | Oct 29 | Nov 11 | Nov 27 |
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 | 136 days | 157 days | 175 days |
| 32°F | 159 days | 179 days | 198 days |
| 28°F | 180 days | 202 days | 222 days |
| 24°F | 203 days | 223 days | 246 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 |
|---|---|---|---|
| 60466 | 6a | -10 to -5°F | 2 km |
| 60461 | 6a | -10 to -5°F | 3 km |
| 60471 | 6a | -10 to -5°F | 4 km |
| 60422 | 6a | -10 to -5°F | 5 km |
| 60475 | 6a | -10 to -5°F | 5 km |
| 60443 | 6a | -10 to -5°F | 6 km |
| 60484 | 6a | -10 to -5°F | 6 km |
| 60430 | 6a | -10 to -5°F | 7 km |
| 60411 | 6a | -10 to -5°F | 8 km |
| 60425 | 6a | -10 to -5°F | 8 km |
| 60478 | 6a | -10 to -5°F | 8 km |
| 60429 | 6a | -10 to -5°F | 9 km |
| 60476 | 6a | -10 to -5°F | 11 km |
| 60417 | 6a | -10 to -5°F | 11 km |
| 60428 | 6a | -10 to -5°F | 12 km |
| 60449 | 6a | -10 to -5°F | 12 km |
| 60477 | 6a | -10 to -5°F | 12 km |
| 60426 | 6a | -10 to -5°F | 13 km |
| 60473 | 6a | -10 to -5°F | 13 km |
| 60438 | 6a | -10 to -5°F | 13 km |
| 60423 | 6a | -10 to -5°F | 14 km |
| 60452 | 6a | -10 to -5°F | 14 km |
| 46311 | 6a | -10 to -5°F | 15 km |
| 60487 | 6a | -10 to -5°F | 15 km |
| 46321 | 6a | -10 to -5°F | 16 km |
| 60419 | 6a | -10 to -5°F | 16 km |
| 60409 | 6a | -10 to -5°F | 17 km |
| 60401 | 6a | -10 to -5°F | 17 km |
| 46324 | 6a | -10 to -5°F | 18 km |
| 46373 | 6a | -10 to -5°F | 19 km |
| 46375 | 6a | -10 to -5°F | 19 km |
| 46322 | 6a | -10 to -5°F | 19 km |
| 46320 | 6a | -10 to -5°F | 20 km |
| 60468 | 6a | -10 to -5°F | 21 km |
| 46323 | 6a | -10 to -5°F | 22 km |
| 46319 | 6a | -10 to -5°F | 22 km |
| 46327 | 6a | -10 to -5°F | 23 km |
| 46312 | 6a | -10 to -5°F | 26 km |
| 46406 | 6a | -10 to -5°F | 26 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 USC00116616, at 41.4947, -87.6803, elevation 216 m (710 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 126.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Chicago Midway Airport 3sw (28 km)
- Little Red School Hse (29 km)
- Chicago Midway Airport (33 km)
- Joliet Brandon Rd Dam (35 km)
- Romeoville WFO (36 km)
- Chicago Northerly Island (41 km)
- Kankakee Metro Wastewater (44 km)
- Lisle-Morton Arboretum (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.