Frost dates for Cahokia, IL
At Cahokia, the median last spring frost (32°F) is Apr 6 and the median first fall frost is Oct 27, for a typical growing season of 203 days. For a 90% chance that the last frost has passed, wait until Apr 20. Nearby ZIP codes are in USDA hardiness zone 7a.
- Apr 6Last spring frost (median)50% chance of 32°F after this date
- Apr 20Safer planting date10% chance of 32°F after this date
- Oct 27First fall frost (median)50% chance of 32°F by this date
- 203 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 4 | Apr 18 | May 3 |
| 32°F | Mar 22 | Apr 6 | Apr 20 |
| 28°F | Mar 11 | Mar 27 | Apr 10 |
| 24°F | Feb 28 | Mar 15 | Mar 31 |
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 5 | Oct 18 | Oct 28 |
| 32°F | Oct 14 | Oct 27 | Nov 7 |
| 28°F | Oct 25 | Nov 5 | Nov 23 |
| 24°F | Nov 3 | Nov 18 | Dec 6 |
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 | 162 days | 181 days | 199 days |
| 32°F | 184 days | 203 days | 223 days |
| 28°F | 205 days | 225 days | 247 days |
| 24°F | 228 days | 247 days | 271 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 |
|---|---|---|---|
| 63118 | 7a | 0 to 5°F | 4 km |
| 63111 | 7a | 0 to 5°F | 5 km |
| 63104 | 7a | 0 to 5°F | 5 km |
| 62240 | 7a | 0 to 5°F | 7 km |
| 63125 | 7a | 0 to 5°F | 10 km |
| 62236 | 7a | 0 to 5°F | 15 km |
| 63129 | 7a | 0 to 5°F | 16 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 USC00111160, at 38.5669, -90.1942, elevation 122 m (400 ft).
- Data quality: Representative (10+ years), 20 years of freeze data.
- Average days per year at or below 32°F: 97.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Cahokia St. Louis Airport (3 km)
- Belleville Siu Rsch (31 km)
- Alton - Melvin Price L&d (34 km)
- Jerseyville 2 SW (61 km)
- Sparta 1 W (65 km)
- Kaskaskia River Navigation Lock (68 km)
- Carlyle Rsvr (73 km)
- Nashville 1 E (77 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.