Frost dates for Walnut, IL
At Walnut, the median last spring frost (32°F) is Apr 24 and the median first fall frost is Oct 14, for a typical growing season of 172 days. For a 90% chance that the last frost has passed, wait until May 9. Nearby ZIP codes are in USDA hardiness zone 5b.
- Apr 24Last spring frost (median)50% chance of 32°F after this date
- May 9Safer planting date10% chance of 32°F after this date
- Oct 14First fall frost (median)50% chance of 32°F by this date
- 172 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 3 | May 20 |
| 32°F | Apr 10 | Apr 24 | May 9 |
| 28°F | Mar 31 | Apr 12 | Apr 29 |
| 24°F | Mar 17 | Apr 3 | Apr 18 |
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 21 | Oct 4 | Oct 16 |
| 32°F | Sep 30 | Oct 14 | Oct 27 |
| 28°F | Oct 11 | Oct 24 | Nov 5 |
| 24°F | Oct 20 | Nov 2 | Nov 17 |
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 | 132 days | 152 days | 169 days |
| 32°F | 152 days | 172 days | 191 days |
| 28°F | 172 days | 193 days | 212 days |
| 24°F | 194 days | 214 days | 235 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 |
|---|---|---|---|
| 61376 | 5b | -15 to -10°F | 2 km |
| 61243 | 5b | -15 to -10°F | 9 km |
| 61338 | 5b | -15 to -10°F | 11 km |
| 61346 | 5b | -15 to -10°F | 11 km |
| 61328 | 5b | -15 to -10°F | 13 km |
| 61349 | 5b | -15 to -10°F | 14 km |
| 61042 | 5b | -15 to -10°F | 15 km |
| 61283 | 5b | -15 to -10°F | 16 km |
| 61374 | 5b | -15 to -10°F | 20 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 USC00118916, at 41.5603, -89.6025, elevation 204 m (671 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 136.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Princeton (25 km)
- Dixon 1w (31 km)
- Hennepin Wtr Trmt Plant (40 km)
- Morrison (40 km)
- Hennepin (41 km)
- Kewanee 1 E (43 km)
- Compton 1 NW (45 km)
- Geneseo (47 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.