Frost dates for 63368 — O Fallon, MO
Last spring frostApr 10median date
First fall frostOct 26median date
Growing season199 daysfrost-free
Hardiness zone6bZone 6b
How O Fallon compares
- In 8 years out of 10, the last spring frost in O Fallon falls between March 26 and April 26, a 31-day window. The first fall frost falls between October 12 and November 8.
- The median last frost is 2 days earlier than the Missouri median of Apr 12.
- Its 199-day growing season is longer than 60% of the 938 Missouri places with a regular frost season (state median 195 days).
- The last frost is 12 days earlier than the zone 6b median of Apr 22. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6b chart.
- The weather station records an average of 105 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 26 |
| 50% (median) | April 10 |
| 10% (safe for tender plants) | April 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 12 |
| 50% (median) | October 26 |
| 90% (late) | November 8 |
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 O Fallon, MO
Frost dates for 63368 — O Fallon, MO — last frost Apr 10, first frost Oct 26, zone 6b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Jan 16 to Jan 30Transplant outside: Mar 13 to Mar 27
Start indoors: Jan 30 to Feb 13Transplant outside: Apr 24 to May 8
Start indoors: Jan 30 to Feb 13Transplant outside: Apr 24 to May 8
Start indoors: Feb 13 to Feb 27Transplant outside: Apr 17 to May 1
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 20 to Apr 3Sow outdoors: Mar 13 to Apr 17Plant for fall: Aug 31 to Sep 28
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 13 to Mar 27Sow outdoors: Mar 13 to Mar 27Plant for fall: Aug 17 to Sep 7
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 20 to Apr 3Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 27 to Mar 13Transplant outside: May 1 to May 15Sow outdoors: May 1 to May 15
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 17 to May 1
Sow outdoors: Feb 27 to Mar 20Plant for fall: Aug 3 to Aug 24
Sow outdoors: Feb 27 to Mar 20Plant for fall: Aug 31 to Sep 21
Sow outdoors: Mar 6 to Apr 17Plant for fall: Sep 14 to Oct 5
Start indoors: Mar 13 to Mar 20Transplant outside: Apr 24 to May 1Sow outdoors: Apr 17 to May 1Plant for fall: Aug 10 to Aug 24
Start indoors: Mar 13 to Mar 20Sow outdoors: Apr 17 to May 1Plant for fall: Aug 17 to Aug 31
Start indoors: Mar 13 to Mar 20Sow outdoors: Apr 17 to May 1
Start indoors: Mar 13 to Mar 20Transplant outside: Apr 24 to May 8
Sow outdoors: Mar 20 to Apr 17Plant for fall: Aug 3 to Aug 17
Sow outdoors: Mar 20 to Apr 17Plant for fall: Aug 17 to Aug 31
Sow outdoors: Mar 20 to Apr 10
Sow outdoors: Mar 27 to Apr 24Plant for fall: Aug 17 to Aug 31
Sow outdoors: Mar 27 to Apr 17Plant for fall: Aug 31 to Sep 21
Sow outdoors: Apr 17 to May 8Plant for fall: Aug 10 to Aug 24
Sow outdoors: Apr 17 to May 1
Transplant outside: Apr 24 to May 15
Plant for fall: Oct 12 to Nov 16
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in O Fallon, MO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 16 – Jan 30 | Mar 13 – Mar 27 | — | — |
| Peppers | Jan 30 – Feb 13 | Apr 24 – May 8 | — | — |
| Eggplant | Jan 30 – Feb 13 | Apr 24 – May 8 | — | — |
| Tomatoes | Feb 13 – Feb 27 | Apr 17 – May 1 | — | — |
| Lettuce | Feb 13 – Feb 27 | Mar 20 – Apr 3 | Mar 13 – Apr 17 | Aug 31 – Sep 28 |
| Kale | Feb 13 – Feb 27 | Mar 13 – Mar 27 | Mar 13 – Mar 27 | Aug 17 – Sep 7 |
| Broccoli | Feb 13 – Feb 27 | Mar 27 – Apr 10 | — | Jul 20 – Aug 10 |
| Cabbage | Feb 13 – Feb 27 | Mar 20 – Apr 3 | — | Jul 20 – Aug 10 |
| Cauliflower | Feb 13 – Feb 27 | Mar 27 – Apr 10 | — | Jul 20 – Aug 10 |
| Okra | Feb 27 – Mar 13 | May 1 – May 15 | May 1 – May 15 | — |
| Basil | Feb 27 – Mar 13 | Apr 17 – May 1 | — | — |
| Peas | — | — | Feb 27 – Mar 20 | Aug 3 – Aug 24 |
| Spinach | — | — | Feb 27 – Mar 20 | Aug 31 – Sep 21 |
| Radishes | — | — | Mar 6 – Apr 17 | Sep 14 – Oct 5 |
| Cucumbers | Mar 13 – Mar 20 | Apr 24 – May 1 | Apr 17 – May 1 | Aug 10 – Aug 24 |
| Zucchini & Summer Squash | Mar 13 – Mar 20 | — | Apr 17 – May 1 | Aug 17 – Aug 31 |
| Winter Squash & Pumpkins | Mar 13 – Mar 20 | — | Apr 17 – May 1 | — |
| Melons & Watermelon | Mar 13 – Mar 20 | Apr 24 – May 8 | — | — |
| Carrots | — | — | Mar 20 – Apr 17 | Aug 3 – Aug 17 |
| Beets | — | — | Mar 20 – Apr 17 | Aug 17 – Aug 31 |
| Potatoes | — | — | Mar 20 – Apr 10 | — |
| Swiss Chard | — | — | Mar 27 – Apr 24 | Aug 17 – Aug 31 |
| Cilantro | — | — | Mar 27 – Apr 17 | Aug 31 – Sep 21 |
| Green Beans | — | — | Apr 17 – May 8 | Aug 10 – Aug 24 |
| Sweet Corn | — | — | Apr 17 – May 1 | — |
| Sweet Potatoes | — | Apr 24 – May 15 | — | — |
| Garlic | — | — | — | Oct 12 – Nov 16 |
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 Weldon Spring Nws, MO weather station, 7 km away (elevation 610 ft (186 m)).
ZIP codes in O Fallon: 63366 63368
Frost dates near O Fallon
- Cottleville Apr 10 · Oct 26
- Lake Saint Louis Apr 10 · Oct 26
- Saint Peters Apr 9 · Oct 26
- Wentzville Apr 10 · Oct 26
- Defiance Apr 10 · Oct 26
- New Melle Apr 10 · Oct 26
- Saint Charles Apr 9 · Oct 26
- Flinthill Apr 9 · Oct 26
Frequently asked questions
When is the last frost in O Fallon, MO?
The median last spring frost in O Fallon, MO is April 10. There is still about a 10% chance of frost after April 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in O Fallon, MO?
The median first fall frost is October 26, with about a 10% chance of frost before October 12.
How long is the growing season in O Fallon, MO?
About 199 days between the median last spring frost and first fall frost.
What planting zone is O Fallon, MO?
O Fallon, MO is in USDA hardiness zone 6b.