Frost dates for 60474South Wilmington, IL
The average last spring frost in South Wilmington is April 27 and the average first fall frost is October 15, giving a typical growing season of about 170 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 27
- Average first fall frost
- Oct 15
- Growing season
- 170 days
Safer after May 14 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 180 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 23 · May 7 · May 26 | Sep 20 · Oct 3 · Oct 17 | 149 days | 100% |
| Frost / freeze (32°F) | Apr 14 · Apr 27 · May 14 | Sep 30 · Oct 15 · Oct 27 | 170 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 17 · May 2 | Oct 13 · Oct 25 · Nov 7 | 192 days | 100% |
Planting calendar for South Wilmington
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 27 – Jun 2 |
| Tomatoes | Transplant outdoors | May 13 – Jun 25 |
| Peppers | Start seeds indoors | Mar 27 – Apr 27 |
| Peppers | Transplant outdoors | May 27 – Jun 27 |
| Eggplant | Start seeds indoors | Apr 13 – May 12 |
| Eggplant | Transplant outdoors | May 27 – Jun 27 |
| Cucumbers | Sow outdoors | May 27 – Jul 5 |
| Summer squash | Sow outdoors | May 13 – Jun 27 |
| Winter squash & pumpkins | Sow outdoors | May 27 – Jun 27 |
| Snap beans | Sow outdoors | May 13 – Jul 28 |
| Sweet corn | Sow outdoors | May 13 – Jun 25 |
| Watermelon & cantaloupe | Sow outdoors | May 27 – Jun 27 |
| Okra | Sow outdoors | May 20 – Jun 12 |
| Peas | Sow outdoors (spring) | Mar 27 – May 12 |
| Potatoes | Plant outdoors (spring) | Mar 27 – May 27 |
| Onions | Start seeds indoors (spring) | Feb 13 – Mar 12 |
| Onions | Transplant outdoors (spring) | Apr 13 – May 12 |
| Broccoli | Start seeds indoors (spring) | Mar 9 – Apr 12 |
| Broccoli | Transplant outdoors (spring) | Apr 13 – May 12 |
| Broccoli | Start seeds indoors (fall) | Jun 15 – Jun 25 |
| Broccoli | Transplant outdoors (fall) | Jul 15 – Jul 26 |
| Cabbage | Start seeds indoors (spring) | Feb 27 – Mar 27 |
| Cabbage | Transplant outdoors (spring) | Mar 27 – Apr 27 |
| Cabbage | Start seeds indoors (fall) | Jun 5 – Jul 5 |
| Cabbage | Transplant outdoors (fall) | Jul 5 – Aug 5 |
| Leaf lettuce | Sow outdoors (spring) | Mar 27 – Jun 12 |
| Leaf lettuce | Sow outdoors (fall) | Jul 5 – Aug 21 |
| Spinach | Sow outdoors (spring) | Mar 20 – May 3 |
| Spinach | Sow outdoors (fall) | Jul 22 – Aug 26 |
| Radishes | Sow outdoors (spring) | Mar 27 – May 17 |
| Radishes | Sow outdoors (fall) | Jul 5 – Sep 5 |
| Kale | Sow outdoors (spring) | Apr 13 – May 3 |
| Kale | Sow outdoors (fall) | Jun 28 – Aug 5 |
| Carrots | Sow outdoors (spring) | Apr 27 – Jun 12 |
| Carrots | Sow outdoors (fall) | Jun 5 – Jul 21 |
| Garlic | Plant outdoors (fall) | Oct 5 – Nov 5 |
Where these dates come from
ZIP code 60474 is matched to the NOAA station Dwight, IL, 13.4 km away, at 628 ft elevation (44 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Dwight, IL (used) | 628 ft | Apr 27 | Oct 15 |
| Channahon Dresden Isl Dam, IL | 505 ft | Apr 16 | Oct 26 |
| Morris 1 Nw, IL | 524 ft | Apr 20 | Oct 23 |
| Kankakee Metro Wastewater, IL | 600 ft | Apr 19 | Oct 24 |
Frost dates near South Wilmington
- Gardner, IL 60424 · last Apr 27, first Oct 15
- Braceville, IL 60407 · last Apr 27, first Oct 15
- Essex, IL 60935 · last Apr 27, first Oct 15
- Reddick, IL 60961 · last Apr 27, first Oct 15
- Braidwood, IL 60408 · last Apr 16, first Oct 26
- Union Hill, IL 60969 · last Apr 19, first Oct 24
- Coal City, IL 60416 · last Apr 16, first Oct 26
- Mazon, IL 60444 · last Apr 27, first Oct 15
Frequently asked questions
- When is the last frost in South Wilmington, IL?
- For ZIP code 60474, the average last spring frost (32°F) is April 27, based on NOAA 1991-2020 climate normals for the Dwight, IL weather station. There is a 1-in-10 chance of a frost after May 14.
- When is the first frost in South Wilmington, IL?
- The average first fall frost (32°F) is October 15. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 60474?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 170 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.