Frost dates for 63366 — O Fallon, MO
Last spring frostApr 9median date
First fall frostOct 26median date
Growing season200 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 27 and April 25, a 29-day window. The first fall frost falls between October 14 and November 7.
- The median last frost is 3 days earlier than the Missouri median of Apr 12.
- Its 200-day growing season is longer than 62% of the 938 Missouri places with a regular frost season (state median 195 days).
- The last frost is 13 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 103 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 27 |
| 50% (median) | April 9 |
| 10% (safe for tender plants) | April 25 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 14 |
| 50% (median) | October 26 |
| 90% (late) | November 7 |
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 63366 — O Fallon, MO — last frost Apr 9, first frost Oct 26, zone 6b. whenisthelastfrost.com
Crop
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Start indoors: Jan 15 to Jan 29Transplant outside: Mar 12 to Mar 26
Start indoors: Jan 29 to Feb 12Transplant outside: Apr 23 to May 7
Start indoors: Jan 29 to Feb 12Transplant outside: Apr 23 to May 7
Start indoors: Feb 12 to Feb 26Transplant outside: Apr 16 to Apr 30
Start indoors: Feb 12 to Feb 26Transplant outside: Mar 19 to Apr 2Sow outdoors: Mar 12 to Apr 16Plant for fall: Aug 31 to Sep 28
Start indoors: Feb 12 to Feb 26Transplant outside: Mar 12 to Mar 26Sow outdoors: Mar 12 to Mar 26Plant for fall: Aug 17 to Sep 7
Start indoors: Feb 12 to Feb 26Transplant outside: Mar 26 to Apr 9Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 12 to Feb 26Transplant outside: Mar 19 to Apr 2Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 12 to Feb 26Transplant outside: Mar 26 to Apr 9Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 30 to May 14Sow outdoors: Apr 30 to May 14
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 16 to Apr 30
Sow outdoors: Feb 26 to Mar 19Plant for fall: Aug 3 to Aug 24
Sow outdoors: Feb 26 to Mar 19Plant for fall: Aug 31 to Sep 21
Sow outdoors: Mar 5 to Apr 16Plant for fall: Sep 14 to Oct 5
Start indoors: Mar 12 to Mar 19Transplant outside: Apr 23 to Apr 30Sow outdoors: Apr 16 to Apr 30Plant for fall: Aug 10 to Aug 24
Start indoors: Mar 12 to Mar 19Sow outdoors: Apr 16 to Apr 30Plant for fall: Aug 17 to Aug 31
Start indoors: Mar 12 to Mar 19Sow outdoors: Apr 16 to Apr 30
Start indoors: Mar 12 to Mar 19Transplant outside: Apr 23 to May 7
Sow outdoors: Mar 19 to Apr 16Plant for fall: Aug 3 to Aug 17
Sow outdoors: Mar 19 to Apr 16Plant for fall: Aug 17 to Aug 31
Sow outdoors: Mar 19 to Apr 9
Sow outdoors: Mar 26 to Apr 23Plant for fall: Aug 17 to Aug 31
Sow outdoors: Mar 26 to Apr 16Plant for fall: Aug 31 to Sep 21
Sow outdoors: Apr 16 to May 7Plant for fall: Aug 10 to Aug 24
Sow outdoors: Apr 16 to Apr 30
Transplant outside: Apr 23 to May 14
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 15 – Jan 29 | Mar 12 – Mar 26 | — | — |
| Peppers | Jan 29 – Feb 12 | Apr 23 – May 7 | — | — |
| Eggplant | Jan 29 – Feb 12 | Apr 23 – May 7 | — | — |
| Tomatoes | Feb 12 – Feb 26 | Apr 16 – Apr 30 | — | — |
| Lettuce | Feb 12 – Feb 26 | Mar 19 – Apr 2 | Mar 12 – Apr 16 | Aug 31 – Sep 28 |
| Kale | Feb 12 – Feb 26 | Mar 12 – Mar 26 | Mar 12 – Mar 26 | Aug 17 – Sep 7 |
| Broccoli | Feb 12 – Feb 26 | Mar 26 – Apr 9 | — | Jul 20 – Aug 10 |
| Cabbage | Feb 12 – Feb 26 | Mar 19 – Apr 2 | — | Jul 20 – Aug 10 |
| Cauliflower | Feb 12 – Feb 26 | Mar 26 – Apr 9 | — | Jul 20 – Aug 10 |
| Okra | Feb 26 – Mar 12 | Apr 30 – May 14 | Apr 30 – May 14 | — |
| Basil | Feb 26 – Mar 12 | Apr 16 – Apr 30 | — | — |
| Peas | — | — | Feb 26 – Mar 19 | Aug 3 – Aug 24 |
| Spinach | — | — | Feb 26 – Mar 19 | Aug 31 – Sep 21 |
| Radishes | — | — | Mar 5 – Apr 16 | Sep 14 – Oct 5 |
| Cucumbers | Mar 12 – Mar 19 | Apr 23 – Apr 30 | Apr 16 – Apr 30 | Aug 10 – Aug 24 |
| Zucchini & Summer Squash | Mar 12 – Mar 19 | — | Apr 16 – Apr 30 | Aug 17 – Aug 31 |
| Winter Squash & Pumpkins | Mar 12 – Mar 19 | — | Apr 16 – Apr 30 | — |
| Melons & Watermelon | Mar 12 – Mar 19 | Apr 23 – May 7 | — | — |
| Carrots | — | — | Mar 19 – Apr 16 | Aug 3 – Aug 17 |
| Beets | — | — | Mar 19 – Apr 16 | Aug 17 – Aug 31 |
| Potatoes | — | — | Mar 19 – Apr 9 | — |
| Swiss Chard | — | — | Mar 26 – Apr 23 | Aug 17 – Aug 31 |
| Cilantro | — | — | Mar 26 – Apr 16 | Aug 31 – Sep 21 |
| Green Beans | — | — | Apr 16 – May 7 | Aug 10 – Aug 24 |
| Sweet Corn | — | — | Apr 16 – Apr 30 | — |
| Sweet Potatoes | — | Apr 23 – May 14 | — | — |
| 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 St Peters 2 Se, MO weather station, 15 km away (elevation 574 ft (175 m)).
ZIP codes in O Fallon: 63366 63368
Frost dates near O Fallon
- Lake Saint Louis Apr 10 · Oct 26
- Wentzville Apr 10 · Oct 26
- Saint Peters Apr 9 · Oct 26
- Cottleville Apr 10 · Oct 26
- Old Monroe Apr 20 · Oct 20
- New Melle Apr 10 · Oct 26
- Foristell Apr 14 · Oct 23
- Saint Charles 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 9. There is still about a 10% chance of frost after April 25, 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 14.
How long is the growing season in O Fallon, MO?
About 200 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.