Last spring frost
Apr 5
Frost Dates for Portage Des Sioux, MO
First fall frost
Oct 27
Growing season
203 days
Hardiness zone
6b
In an average year around Portage Des Sioux, MO, the last spring frost (32°F) is about Apr 5 and the first fall frost is about Oct 27, giving roughly a 203-day growing season. To be safe most years, wait until Mar 22 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 2 | Apr 17 | Apr 4 |
| Freeze (32°F) | Apr 21 | Apr 5 | Mar 22 |
| Hard (28°F) | Apr 9 | Mar 26 | Mar 10 |
| Severe (24°F) | Mar 31 | Mar 15 | Feb 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 2 | Apr 27 | Apr 23 | Apr 20 | Apr 17 | Apr 14 | Apr 11 | Apr 8 | Apr 4 |
| 32°F | Apr 21 | Apr 15 | Apr 11 | Apr 8 | Apr 5 | Apr 2 | Mar 31 | Mar 28 | Mar 22 |
| 28°F | Apr 9 | Apr 4 | Apr 1 | Mar 29 | Mar 26 | Mar 23 | Mar 19 | Mar 16 | Mar 10 |
| 24°F | Mar 31 | Mar 26 | Mar 22 | Mar 18 | Mar 15 | Mar 12 | Mar 9 | Mar 5 | Feb 28 |
| 20°F | Mar 21 | Mar 17 | Mar 13 | Mar 10 | Mar 7 | Mar 3 | Feb 28 | Feb 24 | Feb 16 |
| 16°F | Mar 16 | Mar 11 | Mar 6 | Mar 2 | Feb 28 | Feb 24 | Feb 18 | Feb 13 | Feb 4 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Oct 1 | Oct 17 | Oct 29 |
| Freeze (32°F) | Oct 13 | Oct 27 | Nov 9 |
| Hard (28°F) | Oct 26 | Nov 6 | Nov 24 |
| Severe (24°F) | Nov 3 | Nov 17 | Dec 7 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 6 | Oct 11 | Oct 14 | Oct 17 | Oct 19 | Oct 22 | Oct 25 | Oct 29 |
| 32°F | Oct 13 | Oct 18 | Oct 22 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 3 | Nov 9 |
| 28°F | Oct 26 | Oct 31 | Nov 1 | Nov 4 | Nov 6 | Nov 9 | Nov 13 | Nov 18 | Nov 24 |
| 24°F | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 17 | Nov 21 | Nov 25 | Nov 30 | Dec 7 |
| 20°F | Nov 10 | Nov 17 | Nov 21 | Nov 25 | Nov 30 | Dec 2 | Dec 6 | Dec 11 | Dec 19 |
| 16°F | Nov 21 | Nov 27 | Dec 2 | Dec 6 | Dec 11 | Dec 15 | Dec 20 | Dec 24 | Dec 30 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: St Charles Co Ap, Mo, about 2.3 miles away@if(!empty($station['elevation_ft'])), at 436 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Portage Des Sioux, MO?
On average, the last spring frost (32°F) around Portage Des Sioux, MO is about Apr 5. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 22.
When is the first frost in the fall?
The first fall frost around Portage Des Sioux, MO typically arrives about Oct 27. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 5 on average, or Mar 22 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 203 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 63373 Planting calendar → Missouri frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026