San Jose, IL frost dates
Last spring frostApr 17median date
First fall frostOct 18median date
Growing season184 daysfrost-free
Hardiness zone6aZone 6a
How San Jose compares
- In 8 years out of 10, the last spring frost in San Jose falls between April 4 and May 4, a 30-day window. The first fall frost falls between October 4 and October 30.
- The median last frost is the same as the Illinois median of Apr 17.
- Its 184-day growing season is longer than 42% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 12 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 122 nights a year at or below 32°F.
- Compared with Peoria, IL, 47 km away, the last frost here is 1 day later than there and the growing season is 6 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 4 |
| 50% (median) | April 17 |
| 10% (safe for tender plants) | May 4 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 4 |
| 50% (median) | October 18 |
| 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 San Jose, IL
San Jose, IL frost dates — last frost Apr 17, first frost Oct 18, zone 6a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Jan 23 to Feb 6Transplant outside: Mar 20 to Apr 3
Start indoors: Feb 6 to Feb 20Transplant outside: May 1 to May 15
Start indoors: Feb 6 to Feb 20Transplant outside: May 1 to May 15
Start indoors: Feb 20 to Mar 6Transplant outside: Apr 24 to May 8
Start indoors: Feb 20 to Mar 6Transplant outside: Mar 27 to Apr 10Sow outdoors: Mar 20 to Apr 24Plant for fall: Aug 23 to Sep 20
Start indoors: Feb 20 to Mar 6Transplant outside: Mar 20 to Apr 3Sow outdoors: Mar 20 to Apr 3Plant for fall: Aug 9 to Aug 30
Start indoors: Feb 20 to Mar 6Transplant outside: Apr 3 to Apr 17Plant for fall: Jul 12 to Aug 2
Start indoors: Feb 20 to Mar 6Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 12 to Aug 2
Start indoors: Feb 20 to Mar 6Transplant outside: Apr 3 to Apr 17Plant for fall: Jul 12 to Aug 2
Start indoors: Mar 6 to Mar 20Transplant outside: May 8 to May 22Sow outdoors: May 8 to May 22
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 24 to May 8
Sow outdoors: Mar 6 to Mar 27Plant for fall: Jul 26 to Aug 16
Sow outdoors: Mar 6 to Mar 27Plant for fall: Aug 23 to Sep 13
Sow outdoors: Mar 13 to Apr 24Plant for fall: Sep 6 to Sep 27
Start indoors: Mar 20 to Mar 27Transplant outside: May 1 to May 8Sow outdoors: Apr 24 to May 8Plant for fall: Aug 2 to Aug 16
Start indoors: Mar 20 to Mar 27Sow outdoors: Apr 24 to May 8Plant for fall: Aug 9 to Aug 23
Start indoors: Mar 20 to Mar 27Sow outdoors: Apr 24 to May 8
Start indoors: Mar 20 to Mar 27Transplant outside: May 1 to May 15
Sow outdoors: Mar 27 to Apr 24Plant for fall: Jul 26 to Aug 9
Sow outdoors: Mar 27 to Apr 24Plant for fall: Aug 9 to Aug 23
Sow outdoors: Mar 27 to Apr 17
Sow outdoors: Apr 3 to May 1Plant for fall: Aug 9 to Aug 23
Sow outdoors: Apr 3 to Apr 24Plant for fall: Aug 23 to Sep 13
Sow outdoors: Apr 24 to May 15Plant for fall: Aug 2 to Aug 16
Sow outdoors: Apr 24 to May 8
Transplant outside: May 1 to May 22
Plant for fall: Oct 4 to Nov 8
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in San Jose, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 23 – Feb 6 | Mar 20 – Apr 3 | — | — |
| Peppers | Feb 6 – Feb 20 | May 1 – May 15 | — | — |
| Eggplant | Feb 6 – Feb 20 | May 1 – May 15 | — | — |
| Tomatoes | Feb 20 – Mar 6 | Apr 24 – May 8 | — | — |
| Lettuce | Feb 20 – Mar 6 | Mar 27 – Apr 10 | Mar 20 – Apr 24 | Aug 23 – Sep 20 |
| Kale | Feb 20 – Mar 6 | Mar 20 – Apr 3 | Mar 20 – Apr 3 | Aug 9 – Aug 30 |
| Broccoli | Feb 20 – Mar 6 | Apr 3 – Apr 17 | — | Jul 12 – Aug 2 |
| Cabbage | Feb 20 – Mar 6 | Mar 27 – Apr 10 | — | Jul 12 – Aug 2 |
| Cauliflower | Feb 20 – Mar 6 | Apr 3 – Apr 17 | — | Jul 12 – Aug 2 |
| Okra | Mar 6 – Mar 20 | May 8 – May 22 | May 8 – May 22 | — |
| Basil | Mar 6 – Mar 20 | Apr 24 – May 8 | — | — |
| Peas | — | — | Mar 6 – Mar 27 | Jul 26 – Aug 16 |
| Spinach | — | — | Mar 6 – Mar 27 | Aug 23 – Sep 13 |
| Radishes | — | — | Mar 13 – Apr 24 | Sep 6 – Sep 27 |
| Cucumbers | Mar 20 – Mar 27 | May 1 – May 8 | Apr 24 – May 8 | Aug 2 – Aug 16 |
| Zucchini & Summer Squash | Mar 20 – Mar 27 | — | Apr 24 – May 8 | Aug 9 – Aug 23 |
| Winter Squash & Pumpkins | Mar 20 – Mar 27 | — | Apr 24 – May 8 | — |
| Melons & Watermelon | Mar 20 – Mar 27 | May 1 – May 15 | — | — |
| Carrots | — | — | Mar 27 – Apr 24 | Jul 26 – Aug 9 |
| Beets | — | — | Mar 27 – Apr 24 | Aug 9 – Aug 23 |
| Potatoes | — | — | Mar 27 – Apr 17 | — |
| Swiss Chard | — | — | Apr 3 – May 1 | Aug 9 – Aug 23 |
| Cilantro | — | — | Apr 3 – Apr 24 | Aug 23 – Sep 13 |
| Green Beans | — | — | Apr 24 – May 15 | Aug 2 – Aug 16 |
| Sweet Corn | — | — | Apr 24 – May 8 | — |
| Sweet Potatoes | — | May 1 – May 22 | — | — |
| Garlic | — | — | — | Oct 4 – Nov 8 |
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 Mason City 4se, IL weather station, 16 km away (elevation 600 ft (183 m)).
Frost dates near San Jose
- Mason City Apr 17 · Oct 18
- Green Valley Apr 16 · Oct 23
- Forest City Apr 17 · Oct 19
- Delavan Apr 17 · Oct 18
- Manito Apr 17 · Oct 19
- New Holland Apr 17 · Oct 18
- Emden Apr 20 · Oct 16
- Easton Apr 17 · Oct 19
- Hartsburg Apr 20 · Oct 16
- Topeka Apr 17 · Oct 19
Frequently asked questions
When is the last frost in San Jose, IL?
The median last spring frost in San Jose, IL is April 17. There is still about a 10% chance of frost after May 4, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in San Jose, IL?
The median first fall frost is October 18, with about a 10% chance of frost before October 4.
How long is the growing season in San Jose, IL?
About 184 days between the median last spring frost and first fall frost.
What planting zone is San Jose, IL?
San Jose, IL is in USDA hardiness zone 6a.