Last spring frost
Apr 8
Frost Dates for Washington, MO
First fall frost
Oct 25
Growing season
199 days
Hardiness zone
6b
In an average year around Washington, MO, the last spring frost (32°F) is about Apr 8 and the first fall frost is about Oct 25, giving roughly a 199-day growing season. To be safe most years, wait until Mar 24 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 5 | Apr 20 | Apr 7 |
| Freeze (32°F) | Apr 22 | Apr 8 | Mar 24 |
| Hard (28°F) | Apr 11 | Mar 29 | Mar 12 |
| Severe (24°F) | Apr 1 | Mar 17 | Feb 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 5 | Apr 29 | Apr 25 | Apr 22 | Apr 20 | Apr 17 | Apr 15 | Apr 11 | Apr 7 |
| 32°F | Apr 22 | Apr 17 | Apr 13 | Apr 10 | Apr 8 | Apr 5 | Apr 2 | Mar 31 | Mar 24 |
| 28°F | Apr 11 | Apr 7 | Apr 3 | Apr 1 | Mar 29 | Mar 25 | Mar 21 | Mar 17 | Mar 12 |
| 24°F | Apr 1 | Mar 28 | Mar 23 | Mar 20 | Mar 17 | Mar 15 | Mar 11 | Mar 6 | Feb 28 |
| 20°F | Mar 23 | Mar 18 | Mar 14 | Mar 12 | Mar 8 | Mar 5 | Mar 2 | Feb 27 | Feb 20 |
| 16°F | Mar 17 | Mar 12 | Mar 8 | Mar 4 | Mar 1 | Feb 26 | Feb 21 | Feb 15 | Feb 7 |
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 2 | Oct 16 | Oct 27 |
| Freeze (32°F) | Oct 13 | Oct 25 | Nov 5 |
| Hard (28°F) | Oct 22 | Nov 4 | Nov 21 |
| Severe (24°F) | Nov 1 | Nov 16 | Dec 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 2 | Oct 8 | Oct 11 | Oct 14 | Oct 16 | Oct 18 | Oct 21 | Oct 24 | Oct 27 |
| 32°F | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 27 | Oct 29 | Nov 1 | Nov 5 |
| 28°F | Oct 22 | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 5 | Nov 9 | Nov 14 | Nov 21 |
| 24°F | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 19 | Nov 24 | Nov 29 | Dec 5 |
| 20°F | Nov 9 | Nov 15 | Nov 20 | Nov 25 | Nov 28 | Dec 1 | Dec 5 | Dec 10 | Dec 16 |
| 16°F | Nov 20 | Nov 26 | Nov 30 | Dec 5 | Dec 9 | Dec 14 | Dec 18 | Dec 23 | Dec 28 |
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: Washington, Mo, about 4 miles away@if(!empty($station['elevation_ft'])), at 487 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 Washington, MO?
On average, the last spring frost (32°F) around Washington, MO is about Apr 8. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 24.
When is the first frost in the fall?
The first fall frost around Washington, MO typically arrives about Oct 25. 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 8 on average, or Mar 24 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 199 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 63090 Planting calendar → Missouri frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026