Lemont, IL frost dates
Last spring frostApr 19median date
First fall frostOct 22median date
Growing season186 daysfrost-free
Hardiness zone6aZone 6a
How Lemont compares
- In 8 years out of 10, the last spring frost in Lemont falls between April 6 and May 5, a 29-day window. The first fall frost falls between October 8 and November 3.
- The median last frost is 2 days later than the Illinois median of Apr 17.
- Its 186-day growing season is longer than 46% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 10 days earlier than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 131 nights a year at or below 32°F.
- Compared with Bolingbrook, IL, 12 km away, the last frost here is 1 day earlier than there and the growing season is 1 day longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 6 |
| 50% (median) | April 19 |
| 10% (safe for tender plants) | May 5 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 8 |
| 50% (median) | October 22 |
| 90% (late) | November 3 |
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 Lemont, IL
Lemont, IL frost dates — last frost Apr 19, first frost Oct 22, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Jan 25 to Feb 8Transplant outside: Mar 22 to Apr 5
Start indoors: Feb 8 to Feb 22Transplant outside: May 3 to May 17
Start indoors: Feb 8 to Feb 22Transplant outside: May 3 to May 17
Start indoors: Feb 22 to Mar 8Transplant outside: Apr 26 to May 10
Start indoors: Feb 22 to Mar 8Transplant outside: Mar 29 to Apr 12Sow outdoors: Mar 22 to Apr 26Plant for fall: Aug 27 to Sep 24
Start indoors: Feb 22 to Mar 8Transplant outside: Mar 22 to Apr 5Sow outdoors: Mar 22 to Apr 5Plant for fall: Aug 13 to Sep 3
Start indoors: Feb 22 to Mar 8Transplant outside: Apr 5 to Apr 19Plant for fall: Jul 16 to Aug 6
Start indoors: Feb 22 to Mar 8Transplant outside: Mar 29 to Apr 12Plant for fall: Jul 16 to Aug 6
Start indoors: Feb 22 to Mar 8Transplant outside: Apr 5 to Apr 19Plant for fall: Jul 16 to Aug 6
Start indoors: Mar 8 to Mar 22Transplant outside: May 10 to May 24Sow outdoors: May 10 to May 24
Start indoors: Mar 8 to Mar 22Transplant outside: Apr 26 to May 10
Sow outdoors: Mar 8 to Mar 29Plant for fall: Jul 30 to Aug 20
Sow outdoors: Mar 8 to Mar 29Plant for fall: Aug 27 to Sep 17
Sow outdoors: Mar 15 to Apr 26Plant for fall: Sep 10 to Oct 1
Start indoors: Mar 22 to Mar 29Transplant outside: May 3 to May 10Sow outdoors: Apr 26 to May 10Plant for fall: Aug 6 to Aug 20
Start indoors: Mar 22 to Mar 29Sow outdoors: Apr 26 to May 10Plant for fall: Aug 13 to Aug 27
Start indoors: Mar 22 to Mar 29Sow outdoors: Apr 26 to May 10
Start indoors: Mar 22 to Mar 29Transplant outside: May 3 to May 17
Sow outdoors: Mar 29 to Apr 26Plant for fall: Jul 30 to Aug 13
Sow outdoors: Mar 29 to Apr 26Plant for fall: Aug 13 to Aug 27
Sow outdoors: Mar 29 to Apr 19
Sow outdoors: Apr 5 to May 3Plant for fall: Aug 13 to Aug 27
Sow outdoors: Apr 5 to Apr 26Plant for fall: Aug 27 to Sep 17
Sow outdoors: Apr 26 to May 17Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 26 to May 10
Transplant outside: May 3 to May 24
Plant for fall: Oct 8 to Nov 12
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Lemont, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 25 – Feb 8 | Mar 22 – Apr 5 | — | — |
| Peppers | Feb 8 – Feb 22 | May 3 – May 17 | — | — |
| Eggplant | Feb 8 – Feb 22 | May 3 – May 17 | — | — |
| Tomatoes | Feb 22 – Mar 8 | Apr 26 – May 10 | — | — |
| Lettuce | Feb 22 – Mar 8 | Mar 29 – Apr 12 | Mar 22 – Apr 26 | Aug 27 – Sep 24 |
| Kale | Feb 22 – Mar 8 | Mar 22 – Apr 5 | Mar 22 – Apr 5 | Aug 13 – Sep 3 |
| Broccoli | Feb 22 – Mar 8 | Apr 5 – Apr 19 | — | Jul 16 – Aug 6 |
| Cabbage | Feb 22 – Mar 8 | Mar 29 – Apr 12 | — | Jul 16 – Aug 6 |
| Cauliflower | Feb 22 – Mar 8 | Apr 5 – Apr 19 | — | Jul 16 – Aug 6 |
| Okra | Mar 8 – Mar 22 | May 10 – May 24 | May 10 – May 24 | — |
| Basil | Mar 8 – Mar 22 | Apr 26 – May 10 | — | — |
| Peas | — | — | Mar 8 – Mar 29 | Jul 30 – Aug 20 |
| Spinach | — | — | Mar 8 – Mar 29 | Aug 27 – Sep 17 |
| Radishes | — | — | Mar 15 – Apr 26 | Sep 10 – Oct 1 |
| Cucumbers | Mar 22 – Mar 29 | May 3 – May 10 | Apr 26 – May 10 | Aug 6 – Aug 20 |
| Zucchini & Summer Squash | Mar 22 – Mar 29 | — | Apr 26 – May 10 | Aug 13 – Aug 27 |
| Winter Squash & Pumpkins | Mar 22 – Mar 29 | — | Apr 26 – May 10 | — |
| Melons & Watermelon | Mar 22 – Mar 29 | May 3 – May 17 | — | — |
| Carrots | — | — | Mar 29 – Apr 26 | Jul 30 – Aug 13 |
| Beets | — | — | Mar 29 – Apr 26 | Aug 13 – Aug 27 |
| Potatoes | — | — | Mar 29 – Apr 19 | — |
| Swiss Chard | — | — | Apr 5 – May 3 | Aug 13 – Aug 27 |
| Cilantro | — | — | Apr 5 – Apr 26 | Aug 27 – Sep 17 |
| Green Beans | — | — | Apr 26 – May 17 | Aug 6 – Aug 20 |
| Sweet Corn | — | — | Apr 26 – May 10 | — |
| Sweet Potatoes | — | May 3 – May 24 | — | — |
| Garlic | — | — | — | Oct 8 – Nov 12 |
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 Little Red School Hse, IL weather station, 8 km away (elevation 715 ft (218 m)).
Frost dates near Lemont
- Darien Apr 19 · Oct 22
- Willowbrook Apr 19 · Oct 22
- Westmont Apr 28 · Oct 16
- Woodridge Apr 28 · Oct 16
- Willow Springs Apr 19 · Oct 22
- Downers Grove Apr 28 · Oct 16
- Clarendon Hills Apr 28 · Oct 16
- Romeoville Apr 20 · Oct 22
- Palos Park Apr 19 · Oct 22
- Bolingbrook Apr 20 · Oct 22
Frequently asked questions
When is the last frost in Lemont, IL?
The median last spring frost in Lemont, IL is April 19. There is still about a 10% chance of frost after May 5, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Lemont, IL?
The median first fall frost is October 22, with about a 10% chance of frost before October 8.
How long is the growing season in Lemont, IL?
About 186 days between the median last spring frost and first fall frost.
What planting zone is Lemont, IL?
Lemont, IL is in USDA hardiness zone 6a.