Dayton, MT frost dates
Last spring frostMay 1median date
First fall frostOct 15median date
Growing season167 daysfrost-free
Hardiness zone6aZone 6a
How Dayton compares
- In 8 years out of 10, the last spring frost in Dayton falls between April 16 and May 16, a 30-day window. The first fall frost falls between September 30 and October 30.
- The median last frost is 18 days earlier than the Montana median of May 19.
- Its 167-day growing season is among the longest of the 325 Montana places with a regular frost season.
- The last frost is typical for zone 6a, where the median is Apr 29.
- The weather station records an average of 127 nights a year at or below 32°F.
- Compared with Missoula, MT, 111 km away, the last frost here is 9 days earlier than there and the growing season is 23 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 16 |
| 50% (median) | May 1 |
| 10% (safe for tender plants) | May 16 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 30 |
| 50% (median) | October 15 |
| 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 Dayton, MT
Dayton, MT frost dates — last frost May 1, first frost Oct 15, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Feb 6 to Feb 20Transplant outside: Apr 3 to Apr 17
Start indoors: Feb 20 to Mar 6Transplant outside: May 15 to May 29
Start indoors: Feb 20 to Mar 6Transplant outside: May 15 to May 29
Start indoors: Mar 6 to Mar 20Transplant outside: May 8 to May 22
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 10 to Apr 24Sow outdoors: Apr 3 to May 8Plant for fall: Aug 20 to Sep 17
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 3 to Apr 17Sow outdoors: Apr 3 to Apr 17Plant for fall: Aug 6 to Aug 27
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 17 to May 1Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 10 to Apr 24Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 17 to May 1Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 20 to Apr 3Transplant outside: May 22 to Jun 5Sow outdoors: May 22 to Jun 5
Start indoors: Mar 20 to Apr 3Transplant outside: May 8 to May 22
Sow outdoors: Mar 20 to Apr 10Plant for fall: Jul 23 to Aug 13
Sow outdoors: Mar 20 to Apr 10Plant for fall: Aug 20 to Sep 10
Sow outdoors: Mar 27 to May 8Plant for fall: Sep 3 to Sep 24
Start indoors: Apr 3 to Apr 10Transplant outside: May 15 to May 22Sow outdoors: May 8 to May 22Plant for fall: Jul 30 to Aug 13
Start indoors: Apr 3 to Apr 10Sow outdoors: May 8 to May 22Plant for fall: Aug 6 to Aug 20
Start indoors: Apr 3 to Apr 10Sow outdoors: May 8 to May 22
Start indoors: Apr 3 to Apr 10Transplant outside: May 15 to May 29
Sow outdoors: Apr 10 to May 8Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 10 to May 8Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 10 to May 1
Sow outdoors: Apr 17 to May 15Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 17 to May 8Plant for fall: Aug 20 to Sep 10
Sow outdoors: May 8 to May 29Plant for fall: Jul 30 to Aug 13
Sow outdoors: May 8 to May 22
Transplant outside: May 15 to Jun 5
Plant for fall: Oct 1 to Nov 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Dayton, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 6 – Feb 20 | Apr 3 – Apr 17 | — | — |
| Peppers | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Eggplant | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Tomatoes | Mar 6 – Mar 20 | May 8 – May 22 | — | — |
| Lettuce | Mar 6 – Mar 20 | Apr 10 – Apr 24 | Apr 3 – May 8 | Aug 20 – Sep 17 |
| Kale | Mar 6 – Mar 20 | Apr 3 – Apr 17 | Apr 3 – Apr 17 | Aug 6 – Aug 27 |
| Broccoli | Mar 6 – Mar 20 | Apr 17 – May 1 | — | Jul 9 – Jul 30 |
| Cabbage | Mar 6 – Mar 20 | Apr 10 – Apr 24 | — | Jul 9 – Jul 30 |
| Cauliflower | Mar 6 – Mar 20 | Apr 17 – May 1 | — | Jul 9 – Jul 30 |
| Okra | Mar 20 – Apr 3 | May 22 – Jun 5 | May 22 – Jun 5 | — |
| Basil | Mar 20 – Apr 3 | May 8 – May 22 | — | — |
| Peas | — | — | Mar 20 – Apr 10 | Jul 23 – Aug 13 |
| Spinach | — | — | Mar 20 – Apr 10 | Aug 20 – Sep 10 |
| Radishes | — | — | Mar 27 – May 8 | Sep 3 – Sep 24 |
| Cucumbers | Apr 3 – Apr 10 | May 15 – May 22 | May 8 – May 22 | Jul 30 – Aug 13 |
| Zucchini & Summer Squash | Apr 3 – Apr 10 | — | May 8 – May 22 | Aug 6 – Aug 20 |
| Winter Squash & Pumpkins | Apr 3 – Apr 10 | — | May 8 – May 22 | — |
| Melons & Watermelon | Apr 3 – Apr 10 | May 15 – May 29 | — | — |
| Carrots | — | — | Apr 10 – May 8 | Jul 23 – Aug 6 |
| Beets | — | — | Apr 10 – May 8 | Aug 6 – Aug 20 |
| Potatoes | — | — | Apr 10 – May 1 | — |
| Swiss Chard | — | — | Apr 17 – May 15 | Aug 6 – Aug 20 |
| Cilantro | — | — | Apr 17 – May 8 | Aug 20 – Sep 10 |
| Green Beans | — | — | May 8 – May 29 | Jul 30 – Aug 13 |
| Sweet Corn | — | — | May 8 – May 22 | — |
| Sweet Potatoes | — | May 15 – Jun 5 | — | — |
| Garlic | — | — | — | Oct 1 – Nov 5 |
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 Bigfork 13 S, MT weather station, 19 km away (elevation 2,979 ft (908 m)).
Frost dates near Dayton
- Elmo May 15 · Sep 28
- Big Arm May 15 · Sep 28
- Rollins May 1 · Oct 15
- Proctor May 1 · Oct 15
- Lakeside May 12 · Sep 25
- Polson May 10 · Oct 5
- Somers May 12 · Sep 25
- Bigfork May 12 · Sep 25
- Kila May 12 · Sep 25
- Pablo May 10 · Oct 5
Frequently asked questions
When is the last frost in Dayton, MT?
The median last spring frost in Dayton, MT is May 1. There is still about a 10% chance of frost after May 16, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Dayton, MT?
The median first fall frost is October 15, with about a 10% chance of frost before September 30.
How long is the growing season in Dayton, MT?
About 167 days between the median last spring frost and first fall frost.
What planting zone is Dayton, MT?
Dayton, MT is in USDA hardiness zone 6a.