Frost dates for Polo 5nw, IL
At Polo 5nw, the median last spring frost (32°F) is Apr 29 and the median first fall frost is Oct 7, for a typical growing season of 161 days. For a 90% chance that the last frost has passed, wait until May 14. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- Apr 29Last spring frost (median)50% chance of 32°F after this date
- May 14Safer planting date10% chance of 32°F after this date
- Oct 7First fall frost (median)50% chance of 32°F by this date
- 161 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 24 | May 9 | May 24 |
| 32°F | Apr 15 | Apr 29 | May 14 |
| 28°F | Apr 4 | Apr 19 | May 5 |
| 24°F | Mar 23 | Apr 7 | Apr 25 |
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 14 | Sep 28 | Oct 11 |
| 32°F | Sep 23 | Oct 7 | Oct 22 |
| 28°F | Oct 3 | Oct 19 | Nov 1 |
| 24°F | Oct 15 | Oct 30 | Nov 15 |
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 | 121 days | 142 days | 161 days |
| 32°F | 138 days | 161 days | 180 days |
| 28°F | 160 days | 183 days | 204 days |
| 24°F | 185 days | 206 days | 230 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 |
|---|---|---|---|
| 61064 | 5b | -15 to -10°F | 5 km |
| 61030 | 5b | -15 to -10°F | 10 km |
| 61054 | 5b | -15 to -10°F | 14 km |
| 61051 | 5a | -20 to -15°F | 14 km |
| 61047 | 5b | -15 to -10°F | 22 km |
| 61061 | 5b | -15 to -10°F | 22 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 USC00116897, at 42.0344, -89.6072, elevation 261 m (856 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 138.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Dixon 1w (23 km)
- Freeport Waste Water Plant (29 km)
- Mount Carroll (32 km)
- Morrison (40 km)
- Rockford Gtr Rockford Airport (46 km)
- Rochelle (46 km)
- Fulton L&d #13 (48 km)
- Stockton 3 NNE (51 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.