Frost dates for Chicago Botanic Garden, IL
At Chicago Botanic Garden, the median last spring frost (32°F) is Apr 26 and the median first fall frost is Oct 21, for a typical growing season of 176 days. For a 90% chance that the last frost has passed, wait until May 11. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 26Last spring frost (median)50% chance of 32°F after this date
- May 11Safer planting date10% chance of 32°F after this date
- Oct 21First fall frost (median)50% chance of 32°F by this date
- 176 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 8 | May 26 |
| 32°F | Apr 11 | Apr 26 | May 11 |
| 28°F | Mar 31 | Apr 13 | Apr 28 |
| 24°F | Mar 15 | Mar 31 | Apr 16 |
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 28 | Oct 10 | Oct 24 |
| 32°F | Oct 5 | Oct 21 | Nov 2 |
| 28°F | Oct 17 | Nov 1 | Nov 14 |
| 24°F | Nov 1 | Nov 12 | Nov 28 |
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 | 135 days | 154 days | 174 days |
| 32°F | 155 days | 176 days | 197 days |
| 28°F | 179 days | 202 days | 222 days |
| 24°F | 205 days | 225 days | 247 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 |
|---|---|---|---|
| 60022 | 6a | -10 to -5°F | 2 km |
| 60093 | 6a | -10 to -5°F | 5 km |
| 60035 | 6a | -10 to -5°F | 5 km |
| 60025 | 6a | -10 to -5°F | 8 km |
| 60040 | 6a | -10 to -5°F | 8 km |
| 60043 | 6a | -10 to -5°F | 8 km |
| 60091 | 6a | -10 to -5°F | 9 km |
| 60029 | 6a | -10 to -5°F | 9 km |
| 60053 | 6a | -10 to -5°F | 11 km |
| 60203 | 6a | -10 to -5°F | 12 km |
| 60077 | 6a | -10 to -5°F | 12 km |
| 60201 | 6a | -10 to -5°F | 12 km |
| 60045 | 6a | -10 to -5°F | 13 km |
| 60076 | 6a | -10 to -5°F | 13 km |
| 60208 | 6a | -10 to -5°F | 14 km |
| 60202 | 6a | -10 to -5°F | 15 km |
| 60712 | 6a | -10 to -5°F | 16 km |
| 60645 | 6a | -10 to -5°F | 16 km |
| 60626 | 6a | -10 to -5°F | 18 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 USC00111497, at 42.1400, -87.7853, elevation 192 m (630 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 128.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Chicago Palwaukee Airport (10 km)
- Chicago Ohare Intl Airport (20 km)
- Waukegan (25 km)
- Mundelein 4 WSW (27 km)
- Barrington 3sw (31 km)
- Chicago Waukegan Regional Airport (31 km)
- Chicago Northerly Island (35 km)
- Streamwood (35 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.