Frost dates for Pontiac, IL
At Pontiac, the median last spring frost (32°F) is Apr 16 and the median first fall frost is Oct 24, for a typical growing season of 191 days. For a 90% chance that the last frost has passed, wait until May 2. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- Apr 16Last spring frost (median)50% chance of 32°F after this date
- May 2Safer planting date10% chance of 32°F after this date
- Oct 24First fall frost (median)50% chance of 32°F by this date
- 191 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 13 | Apr 26 | May 11 |
| 32°F | Apr 3 | Apr 16 | May 2 |
| 28°F | Mar 20 | Apr 4 | Apr 19 |
| 24°F | Mar 9 | Mar 26 | Apr 9 |
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 | Oct 2 | Oct 15 | Oct 27 |
| 32°F | Oct 12 | Oct 24 | Nov 5 |
| 28°F | Oct 23 | Nov 3 | Nov 18 |
| 24°F | Nov 1 | Nov 14 | Nov 29 |
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 | 170 days | 188 days |
| 32°F | 171 days | 191 days | 210 days |
| 28°F | 192 days | 213 days | 234 days |
| 24°F | 214 days | 234 days | 256 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 |
|---|---|---|---|
| 61764 | 6a | -10 to -5°F | 1 km |
| 61743 | 5b | -15 to -10°F | 12 km |
| 60460 | 6a | -10 to -5°F | 16 km |
| 61769 | 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 USC00116910, at 40.8778, -88.6364, elevation 198 m (650 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 122.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Chenoa (17 km)
- Streator 3 SE (28 km)
- Dwight (32 km)
- Minonk (34 km)
- Piper City (40 km)
- Normal 4ne (45 km)
- Gibson City (50 km)
- Marseilles Lock (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.