Lake Forest, IL frost dates
Last spring frostApr 26median date
First fall frostOct 21median date
Growing season178 daysfrost-free
Hardiness zone6aZone 6a
How Lake Forest compares
- In 8 years out of 10, the last spring frost in Lake Forest falls between April 11 and May 11, a 30-day window. The first fall frost falls between October 5 and November 2.
- The median last frost is 9 days later than the Illinois median of Apr 17.
- Its 178-day growing season is longer than 24% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is typical for zone 6a, where the median is Apr 29.
- The weather station records an average of 128 nights a year at or below 32°F.
- Compared with Waukegan, IL, 15 km away, the last frost here is 4 days earlier than there and the growing season is 6 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 11 |
| 50% (median) | April 26 |
| 10% (safe for tender plants) | May 11 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 5 |
| 50% (median) | October 21 |
| 90% (late) | November 2 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Lake Forest, IL
Lake Forest, IL frost dates — last frost Apr 26, first frost Oct 21, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Feb 1 to Feb 15Transplant outside: Mar 29 to Apr 12
Start indoors: Feb 15 to Mar 1Transplant outside: May 10 to May 24
Start indoors: Feb 15 to Mar 1Transplant outside: May 10 to May 24
Start indoors: Mar 1 to Mar 15Transplant outside: May 3 to May 17
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 5 to Apr 19Sow outdoors: Mar 29 to May 3Plant for fall: Aug 26 to Sep 23
Start indoors: Mar 1 to Mar 15Transplant outside: Mar 29 to Apr 12Sow outdoors: Mar 29 to Apr 12Plant for fall: Aug 12 to Sep 2
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 12 to Apr 26Plant for fall: Jul 15 to Aug 5
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 5 to Apr 19Plant for fall: Jul 15 to Aug 5
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 12 to Apr 26Plant for fall: Jul 15 to Aug 5
Start indoors: Mar 15 to Mar 29Transplant outside: May 17 to May 31Sow outdoors: May 17 to May 31
Start indoors: Mar 15 to Mar 29Transplant outside: May 3 to May 17
Sow outdoors: Mar 15 to Apr 5Plant for fall: Jul 29 to Aug 19
Sow outdoors: Mar 15 to Apr 5Plant for fall: Aug 26 to Sep 16
Sow outdoors: Mar 22 to May 3Plant for fall: Sep 9 to Sep 30
Start indoors: Mar 29 to Apr 5Transplant outside: May 10 to May 17Sow outdoors: May 3 to May 17Plant for fall: Aug 5 to Aug 19
Start indoors: Mar 29 to Apr 5Sow outdoors: May 3 to May 17Plant for fall: Aug 12 to Aug 26
Start indoors: Mar 29 to Apr 5Sow outdoors: May 3 to May 17
Start indoors: Mar 29 to Apr 5Transplant outside: May 10 to May 24
Sow outdoors: Apr 5 to May 3Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 5 to May 3Plant for fall: Aug 12 to Aug 26
Sow outdoors: Apr 5 to Apr 26
Sow outdoors: Apr 12 to May 10Plant for fall: Aug 12 to Aug 26
Sow outdoors: Apr 12 to May 3Plant for fall: Aug 26 to Sep 16
Sow outdoors: May 3 to May 24Plant for fall: Aug 5 to Aug 19
Sow outdoors: May 3 to May 17
Transplant outside: May 10 to May 31
Plant for fall: Oct 7 to Nov 11
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Lake Forest, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 1 – Feb 15 | Mar 29 – Apr 12 | — | — |
| Peppers | Feb 15 – Mar 1 | May 10 – May 24 | — | — |
| Eggplant | Feb 15 – Mar 1 | May 10 – May 24 | — | — |
| Tomatoes | Mar 1 – Mar 15 | May 3 – May 17 | — | — |
| Lettuce | Mar 1 – Mar 15 | Apr 5 – Apr 19 | Mar 29 – May 3 | Aug 26 – Sep 23 |
| Kale | Mar 1 – Mar 15 | Mar 29 – Apr 12 | Mar 29 – Apr 12 | Aug 12 – Sep 2 |
| Broccoli | Mar 1 – Mar 15 | Apr 12 – Apr 26 | — | Jul 15 – Aug 5 |
| Cabbage | Mar 1 – Mar 15 | Apr 5 – Apr 19 | — | Jul 15 – Aug 5 |
| Cauliflower | Mar 1 – Mar 15 | Apr 12 – Apr 26 | — | Jul 15 – Aug 5 |
| Okra | Mar 15 – Mar 29 | May 17 – May 31 | May 17 – May 31 | — |
| Basil | Mar 15 – Mar 29 | May 3 – May 17 | — | — |
| Peas | — | — | Mar 15 – Apr 5 | Jul 29 – Aug 19 |
| Spinach | — | — | Mar 15 – Apr 5 | Aug 26 – Sep 16 |
| Radishes | — | — | Mar 22 – May 3 | Sep 9 – Sep 30 |
| Cucumbers | Mar 29 – Apr 5 | May 10 – May 17 | May 3 – May 17 | Aug 5 – Aug 19 |
| Zucchini & Summer Squash | Mar 29 – Apr 5 | — | May 3 – May 17 | Aug 12 – Aug 26 |
| Winter Squash & Pumpkins | Mar 29 – Apr 5 | — | May 3 – May 17 | — |
| Melons & Watermelon | Mar 29 – Apr 5 | May 10 – May 24 | — | — |
| Carrots | — | — | Apr 5 – May 3 | Jul 29 – Aug 12 |
| Beets | — | — | Apr 5 – May 3 | Aug 12 – Aug 26 |
| Potatoes | — | — | Apr 5 – Apr 26 | — |
| Swiss Chard | — | — | Apr 12 – May 10 | Aug 12 – Aug 26 |
| Cilantro | — | — | Apr 12 – May 3 | Aug 26 – Sep 16 |
| Green Beans | — | — | May 3 – May 24 | Aug 5 – Aug 19 |
| Sweet Corn | — | — | May 3 – May 17 | — |
| Sweet Potatoes | — | May 10 – May 31 | — | — |
| Garlic | — | — | — | Oct 7 – Nov 11 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Chicago Botanic Garden, IL weather station, 12 km away (elevation 630 ft (192 m)).
Frost dates near Lake Forest
- Fort Sheridan Apr 26 · Oct 21
- Highwood Apr 26 · Oct 21
- Lake Bluff Apr 30 · Oct 19
- Highland Park Apr 26 · Oct 21
- Great Lakes Apr 30 · Oct 19
- Deerfield Apr 19 · Oct 26
- Lincolnshire Apr 19 · Oct 26
- Libertyville Apr 30 · Oct 19
- Vernon Hills Apr 29 · Oct 20
- Northbrook Apr 26 · Oct 21
Frequently asked questions
When is the last frost in Lake Forest, IL?
The median last spring frost in Lake Forest, IL is April 26. There is still about a 10% chance of frost after May 11, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Lake Forest, IL?
The median first fall frost is October 21, with about a 10% chance of frost before October 5.
How long is the growing season in Lake Forest, IL?
About 178 days between the median last spring frost and first fall frost.
What planting zone is Lake Forest, IL?
Lake Forest, IL is in USDA hardiness zone 6a.