Frost dates for Harrisburg, IL
At Harrisburg, the median last spring frost (32°F) is Apr 7 and the median first fall frost is Oct 26, for a typical growing season of 202 days. For a 90% chance that the last frost has passed, wait until Apr 25. Nearby ZIP codes are in USDA hardiness zone 7a.
- Apr 7Last spring frost (median)50% chance of 32°F after this date
- Apr 25Safer planting date10% chance of 32°F after this date
- Oct 26First fall frost (median)50% chance of 32°F by this date
- 202 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 3 | Apr 19 | May 5 |
| 32°F | Mar 21 | Apr 7 | Apr 25 |
| 28°F | Mar 7 | Mar 26 | Apr 12 |
| 24°F | Feb 21 | Mar 12 | Mar 30 |
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 1 | Oct 16 | Oct 28 |
| 32°F | Oct 10 | Oct 26 | Nov 8 |
| 28°F | Oct 23 | Nov 6 | Nov 25 |
| 24°F | Nov 3 | Nov 19 | Dec 9 |
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 | 158 days | 180 days | 200 days |
| 32°F | 180 days | 202 days | 224 days |
| 28°F | 202 days | 226 days | 251 days |
| 24°F | 229 days | 252 days | 279 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 |
|---|---|---|---|
| 62965 | 7a | 0 to 5°F | 3 km |
| 62946 | 7a | 0 to 5°F | 4 km |
| 62917 | 7a | 0 to 5°F | 12 km |
| 62977 | 7a | 0 to 5°F | 13 km |
| 62930 | 7a | 0 to 5°F | 14 km |
| 62934 | 7a | 0 to 5°F | 15 km |
| 62935 | 7a | 0 to 5°F | 15 km |
| 62987 | 7a | 0 to 5°F | 18 km |
| 62954 | 7a | 0 to 5°F | 23 km |
| 62974 | 7a | 0 to 5°F | 24 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 USC00113879, at 37.7408, -88.5244, elevation 111 m (365 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 95.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Rosiclare 5nw (31 km)
- Dixon Springs Agric Center (36 km)
- McLeansboro (38 km)
- Benton 2 N (48 km)
- Carmi 3 (48 km)
- Rend Lake Dam (53 km)
- Carbondale Sewage Plant (56 km)
- Carbondale Southern Il Airport (64 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.