Frost dates for Rockford Gtr Rockford Airport, IL
At Rockford Gtr Rockford Airport, the median last spring frost (32°F) is Apr 24 and the median first fall frost is Oct 17, for a typical growing season of 174 days. For a 90% chance that the last frost has passed, wait until May 8. Nearby ZIP codes are in USDA hardiness zone 5b.
- Apr 24Last spring frost (median)50% chance of 32°F after this date
- May 8Safer planting date10% chance of 32°F after this date
- Oct 17First fall frost (median)50% chance of 32°F by this date
- 174 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 21 | May 4 | May 19 |
| 32°F | Apr 10 | Apr 24 | May 8 |
| 28°F | Mar 31 | Apr 13 | Apr 27 |
| 24°F | Mar 16 | Apr 2 | 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 23 | Oct 6 | Oct 20 |
| 32°F | Oct 2 | Oct 17 | Oct 30 |
| 28°F | Oct 14 | Oct 28 | Nov 10 |
| 24°F | Oct 26 | Nov 6 | Nov 23 |
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 | 134 days | 153 days | 173 days |
| 32°F | 154 days | 174 days | 192 days |
| 28°F | 177 days | 197 days | 217 days |
| 24°F | 200 days | 219 days | 241 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 |
|---|---|---|---|
| 61109 | 5b | -15 to -10°F | 3 km |
| 61104 | 5b | -15 to -10°F | 7 km |
| 61102 | 5b | -15 to -10°F | 7 km |
| 61020 | 5b | -15 to -10°F | 9 km |
| 61108 | 5b | -15 to -10°F | 10 km |
| 61084 | 5b | -15 to -10°F | 11 km |
| 61112 | 5b | -15 to -10°F | 11 km |
| 61052 | 5b | -15 to -10°F | 12 km |
| 61016 | 5b | -15 to -10°F | 12 km |
| 61107 | 5b | -15 to -10°F | 13 km |
| 61043 | 5b | -15 to -10°F | 14 km |
| 61114 | 5b | -15 to -10°F | 15 km |
| 61010 | 5b | -15 to -10°F | 16 km |
| 61088 | 5b | -15 to -10°F | 16 km |
| 61103 | 5b | -15 to -10°F | 16 km |
| 61111 | 5b | -15 to -10°F | 18 km |
| 61101 | 5b | -15 to -10°F | 18 km |
| 61077 | 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 USW00094822, at 42.1928, -89.0931, elevation 222 m (730 ft).
- Data quality: Standard (24+ years of data), 30 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
- Rochelle (31 km)
- De Kalb (39 km)
- Marengo (41 km)
- Freeport Waste Water Plant (44 km)
- Shabbona 5 NNE (44 km)
- Polo 5nw (46 km)
- Dixon 1w (53 km)
- Compton 1 NW (54 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.