Last spring frost
Apr 9
Frost Dates for Carterville, IL
First fall frost
Oct 22
Growing season
195 days
Hardiness zone
7a
In an average year around Carterville, IL, the last spring frost (32°F) is about Apr 9 and the first fall frost is about Oct 22, giving roughly a 195-day growing season. To be safe most years, wait until Mar 25 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 5 | Apr 22 | Apr 5 |
| Freeze (32°F) | Apr 25 | Apr 9 | Mar 25 |
| Hard (28°F) | Apr 14 | Mar 29 | Mar 11 |
| Severe (24°F) | Apr 2 | Mar 17 | Feb 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 5 | May 2 | Apr 29 | Apr 25 | Apr 22 | Apr 19 | Apr 15 | Apr 11 | Apr 5 |
| 32°F | Apr 25 | Apr 20 | Apr 16 | Apr 12 | Apr 9 | Apr 5 | Apr 2 | Mar 30 | Mar 25 |
| 28°F | Apr 14 | Apr 8 | Apr 4 | Mar 31 | Mar 29 | Mar 26 | Mar 22 | Mar 18 | Mar 11 |
| 24°F | Apr 2 | Mar 29 | Mar 25 | Mar 21 | Mar 17 | Mar 13 | Mar 10 | Mar 5 | Feb 28 |
| 20°F | Mar 22 | Mar 17 | Mar 14 | Mar 10 | Mar 6 | Mar 3 | Feb 28 | Feb 22 | Feb 14 |
| 16°F | Mar 15 | Mar 9 | Mar 5 | Mar 1 | Feb 25 | Feb 20 | Feb 14 | Feb 7 | Feb 1 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 30 | Oct 13 | Oct 25 |
| Freeze (32°F) | Oct 10 | Oct 22 | Nov 2 |
| Hard (28°F) | Oct 19 | Nov 1 | Nov 18 |
| Severe (24°F) | Oct 30 | Nov 13 | Dec 3 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 30 | Oct 4 | Oct 8 | Oct 10 | Oct 13 | Oct 15 | Oct 18 | Oct 21 | Oct 25 |
| 32°F | Oct 10 | Oct 14 | Oct 18 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Oct 30 | Nov 2 |
| 28°F | Oct 19 | Oct 24 | Oct 27 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 11 | Nov 18 |
| 24°F | Oct 30 | Nov 2 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 22 | Nov 27 | Dec 3 |
| 20°F | Nov 8 | Nov 13 | Nov 18 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 10 | Dec 18 |
| 16°F | Nov 18 | Nov 26 | Dec 1 | Dec 5 | Dec 10 | Dec 15 | Dec 21 | Dec 26 | Jan 1 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Carbondale Sewage Plt, Il, about 5.8 miles away@if(!empty($station['elevation_ft'])), at 390 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Carterville, IL?
On average, the last spring frost (32°F) around Carterville, IL is about Apr 9. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 25.
When is the first frost in the fall?
The first fall frost around Carterville, IL typically arrives about Oct 22. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 9 on average, or Mar 25 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 195 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 62918 Planting calendar → Illinois frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026