Byron, IL frost dates
Last spring frostApr 24median date
First fall frostOct 17median date
Growing season176 daysfrost-free
Hardiness zone5bZone 5b
How Byron compares
- In 8 years out of 10, the last spring frost in Byron falls between April 10 and May 8, a 28-day window. The first fall frost falls between October 2 and October 30.
- The median last frost is 7 days later than the Illinois median of Apr 17.
- Its 176-day growing season is longer than 19% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 7 days earlier than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 136 nights a year at or below 32°F.
- Byron shares its weather station with Rockford, IL, 23 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 10 |
| 50% (median) | April 24 |
| 10% (safe for tender plants) | May 8 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 2 |
| 50% (median) | October 17 |
| 90% (late) | October 30 |
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 Byron, IL
Byron, IL frost dates — last frost Apr 24, first frost Oct 17, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Jan 30 to Feb 13Transplant outside: Mar 27 to Apr 10
Start indoors: Feb 13 to Feb 27Transplant outside: May 8 to May 22
Start indoors: Feb 13 to Feb 27Transplant outside: May 8 to May 22
Start indoors: Feb 27 to Mar 13Transplant outside: May 1 to May 15
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 3 to Apr 17Sow outdoors: Mar 27 to May 1Plant for fall: Aug 22 to Sep 19
Start indoors: Feb 27 to Mar 13Transplant outside: Mar 27 to Apr 10Sow outdoors: Mar 27 to Apr 10Plant for fall: Aug 8 to Aug 29
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 10 to Apr 24Plant for fall: Jul 11 to Aug 1
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 3 to Apr 17Plant for fall: Jul 11 to Aug 1
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 10 to Apr 24Plant for fall: Jul 11 to Aug 1
Start indoors: Mar 13 to Mar 27Transplant outside: May 15 to May 29Sow outdoors: May 15 to May 29
Start indoors: Mar 13 to Mar 27Transplant outside: May 1 to May 15
Sow outdoors: Mar 13 to Apr 3Plant for fall: Jul 25 to Aug 15
Sow outdoors: Mar 13 to Apr 3Plant for fall: Aug 22 to Sep 12
Sow outdoors: Mar 20 to May 1Plant for fall: Sep 5 to Sep 26
Start indoors: Mar 27 to Apr 3Transplant outside: May 8 to May 15Sow outdoors: May 1 to May 15Plant for fall: Aug 1 to Aug 15
Start indoors: Mar 27 to Apr 3Sow outdoors: May 1 to May 15Plant for fall: Aug 8 to Aug 22
Start indoors: Mar 27 to Apr 3Sow outdoors: May 1 to May 15
Start indoors: Mar 27 to Apr 3Transplant outside: May 8 to May 22
Sow outdoors: Apr 3 to May 1Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 3 to May 1Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 3 to Apr 24
Sow outdoors: Apr 10 to May 8Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 10 to May 1Plant for fall: Aug 22 to Sep 12
Sow outdoors: May 1 to May 22Plant for fall: Aug 1 to Aug 15
Sow outdoors: May 1 to May 15
Transplant outside: May 8 to May 29
Plant for fall: Oct 3 to Nov 7
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Byron, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 30 – Feb 13 | Mar 27 – Apr 10 | — | — |
| Peppers | Feb 13 – Feb 27 | May 8 – May 22 | — | — |
| Eggplant | Feb 13 – Feb 27 | May 8 – May 22 | — | — |
| Tomatoes | Feb 27 – Mar 13 | May 1 – May 15 | — | — |
| Lettuce | Feb 27 – Mar 13 | Apr 3 – Apr 17 | Mar 27 – May 1 | Aug 22 – Sep 19 |
| Kale | Feb 27 – Mar 13 | Mar 27 – Apr 10 | Mar 27 – Apr 10 | Aug 8 – Aug 29 |
| Broccoli | Feb 27 – Mar 13 | Apr 10 – Apr 24 | — | Jul 11 – Aug 1 |
| Cabbage | Feb 27 – Mar 13 | Apr 3 – Apr 17 | — | Jul 11 – Aug 1 |
| Cauliflower | Feb 27 – Mar 13 | Apr 10 – Apr 24 | — | Jul 11 – Aug 1 |
| Okra | Mar 13 – Mar 27 | May 15 – May 29 | May 15 – May 29 | — |
| Basil | Mar 13 – Mar 27 | May 1 – May 15 | — | — |
| Peas | — | — | Mar 13 – Apr 3 | Jul 25 – Aug 15 |
| Spinach | — | — | Mar 13 – Apr 3 | Aug 22 – Sep 12 |
| Radishes | — | — | Mar 20 – May 1 | Sep 5 – Sep 26 |
| Cucumbers | Mar 27 – Apr 3 | May 8 – May 15 | May 1 – May 15 | Aug 1 – Aug 15 |
| Zucchini & Summer Squash | Mar 27 – Apr 3 | — | May 1 – May 15 | Aug 8 – Aug 22 |
| Winter Squash & Pumpkins | Mar 27 – Apr 3 | — | May 1 – May 15 | — |
| Melons & Watermelon | Mar 27 – Apr 3 | May 8 – May 22 | — | — |
| Carrots | — | — | Apr 3 – May 1 | Jul 25 – Aug 8 |
| Beets | — | — | Apr 3 – May 1 | Aug 8 – Aug 22 |
| Potatoes | — | — | Apr 3 – Apr 24 | — |
| Swiss Chard | — | — | Apr 10 – May 8 | Aug 8 – Aug 22 |
| Cilantro | — | — | Apr 10 – May 1 | Aug 22 – Sep 12 |
| Green Beans | — | — | May 1 – May 22 | Aug 1 – Aug 15 |
| Sweet Corn | — | — | May 1 – May 15 | — |
| Sweet Potatoes | — | May 8 – May 29 | — | — |
| Garlic | — | — | — | Oct 3 – Nov 7 |
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 Rockford Gtr Rockford Ap, IL weather station, 16 km away (elevation 732 ft (223 m)).
Frost dates near Byron
- Stillman Valley Apr 24 · Oct 17
- Leaf River Apr 29 · Oct 7
- Seward Apr 26 · Oct 13
- Oregon Apr 29 · Oct 7
- Davis Junction Apr 24 · Oct 17
- Holcomb Apr 24 · Oct 17
- Chana Apr 26 · Oct 13
- Winnebago Apr 24 · Oct 17
- Mount Morris Apr 29 · Oct 7
- German Valley Apr 26 · Oct 13
Frequently asked questions
When is the last frost in Byron, IL?
The median last spring frost in Byron, IL is April 24. There is still about a 10% chance of frost after May 8, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Byron, IL?
The median first fall frost is October 17, with about a 10% chance of frost before October 2.
How long is the growing season in Byron, IL?
About 176 days between the median last spring frost and first fall frost.
What planting zone is Byron, IL?
Byron, IL is in USDA hardiness zone 5b.