Frost dates for 60527Willowbrook, IL
The average last spring frost in Willowbrook is April 27 and the average first fall frost is October 17, giving a typical growing season of about 173 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 27
- Average first fall frost
- Oct 17
- Growing season
- 173 days
Safer after May 14 (1-in-10 risk)
Possible by Oct 1 (1-in-10 risk)
Last frost typically in 179 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 8 · May 26 | Sep 22 · Oct 6 · Oct 22 | 150 days | 100% |
| Frost / freeze (32°F) | Apr 12 · Apr 27 · May 14 | Oct 1 · Oct 17 · Nov 2 | 173 days | 100% |
| Hard freeze (28°F) | Mar 31 · Apr 16 · May 1 | Oct 12 · Oct 29 · Nov 14 | 195 days | 100% |
Planting calendar for Willowbrook
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 27 |
| 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 7 |
| Summer squash | Sow outdoors | May 13 – Jun 27 |
| Winter squash & pumpkins | Sow outdoors | May 27 – Jun 27 |
| Snap beans | Sow outdoors | May 13 – Jul 30 |
| Sweet corn | Sow outdoors | May 13 – Jun 27 |
| 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 17 – Jun 27 |
| Broccoli | Transplant outdoors (fall) | Jul 17 – Jul 28 |
| Cabbage | Start seeds indoors (spring) | Feb 27 – Mar 27 |
| Cabbage | Transplant outdoors (spring) | Mar 27 – Apr 27 |
| Cabbage | Start seeds indoors (fall) | Jun 7 – Jul 7 |
| Cabbage | Transplant outdoors (fall) | Jul 7 – Aug 7 |
| Leaf lettuce | Sow outdoors (spring) | Mar 27 – Jun 12 |
| Leaf lettuce | Sow outdoors (fall) | Jul 7 – Aug 23 |
| Spinach | Sow outdoors (spring) | Mar 20 – May 3 |
| Spinach | Sow outdoors (fall) | Jul 24 – Aug 28 |
| Radishes | Sow outdoors (spring) | Mar 27 – May 17 |
| Radishes | Sow outdoors (fall) | Jul 7 – Sep 7 |
| Kale | Sow outdoors (spring) | Apr 13 – May 3 |
| Kale | Sow outdoors (fall) | Jun 30 – Aug 7 |
| Carrots | Sow outdoors (spring) | Apr 27 – Jun 12 |
| Carrots | Sow outdoors (fall) | Jun 7 – Jul 23 |
| Garlic | Plant outdoors (fall) | Oct 7 – Nov 7 |
Where these dates come from
ZIP code 60527 is matched to the NOAA station Wheaton 3 Se, IL, 13.8 km away, at 680 ft elevation (42 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Wheaton 3 Se, IL (used) | 680 ft | Apr 27 | Oct 17 |
| Little Red School Hse, IL | 715 ft | Apr 19 | Oct 22 |
| Chicago Midway Ap 3Sw, IL | 620 ft | Apr 10 | Nov 1 |
| Lisle-Morton Arboretum, IL | 680 ft | Apr 28 | Oct 16 |
Frost dates near Willowbrook
- Darien, IL 60561 · last Apr 27, first Oct 17
- Willow Springs, IL 60480 · last Apr 10, first Nov 1
- Westmont, IL 60559 · last Apr 27, first Oct 17
- Lemont, IL 60439 · last Apr 27, first Oct 17
- Clarendon Hills, IL 60514 · last Apr 27, first Oct 17
- Hinsdale, IL 60521 · last Apr 27, first Oct 17
- La Grange, IL 60525 · last Apr 10, first Nov 1
- Downers Grove, IL 60516 · last Apr 27, first Oct 17
Frequently asked questions
- When is the last frost in Willowbrook, IL?
- For ZIP code 60527, the average last spring frost (32°F) is April 27, based on NOAA 1991-2020 climate normals for the Wheaton 3 Se, IL weather station. There is a 1-in-10 chance of a frost after May 14.
- When is the first frost in Willowbrook, IL?
- The average first fall frost (32°F) is October 17. There is a 1-in-10 chance of frost by October 1, so tender plants are at risk from that point on.
- How long is the growing season in 60527?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 173 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.