Avon, MT frost dates
Last spring frostJun 9median date
First fall frostSep 8median date
Growing season91 daysfrost-free
Hardiness zone4bZone 4b
How Avon compares
- In 8 years out of 10, the last spring frost in Avon falls between May 23 and June 26, a 34-day window. The first fall frost falls between August 26 and September 21.
- The median last frost is 21 days later than the Montana median of May 19.
- Its 91-day growing season is longer than 6% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 32 days later than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 219 nights a year at or below 32°F.
- Compared with Missoula, MT, 113 km away, the last frost here is 30 days later than there and the growing season is 53 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 23 |
| 50% (median) | June 9 |
| 10% (safe for tender plants) | June 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 26 |
| 50% (median) | September 8 |
| 90% (late) | September 21 |
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 Avon, MT
Avon, MT frost dates — last frost Jun 9, first frost Sep 8, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Mar 17 to Mar 31Transplant outside: May 12 to May 26
Start indoors: Mar 31 to Apr 14Transplant outside: Jun 23 to Jul 7
Start indoors: Mar 31 to Apr 14Transplant outside: Jun 23 to Jul 7
Start indoors: Apr 14 to Apr 28Transplant outside: Jun 16 to Jun 30
Start indoors: Apr 14 to Apr 28Transplant outside: May 19 to Jun 2Sow outdoors: May 12 to Jun 16Plant for fall: Jul 14 to Aug 11
Start indoors: Apr 14 to Apr 28Transplant outside: May 12 to May 26Sow outdoors: May 12 to May 26Plant for fall: Jun 30 to Jul 21
Start indoors: Apr 14 to Apr 28Transplant outside: May 26 to Jun 9
Start indoors: Apr 14 to Apr 28Transplant outside: May 19 to Jun 2
Start indoors: Apr 14 to Apr 28Transplant outside: May 26 to Jun 9
Start indoors: Apr 28 to May 12Transplant outside: Jun 30 to Jul 14Sow outdoors: Jun 30 to Jul 14
Start indoors: Apr 28 to May 12Transplant outside: Jun 16 to Jun 30
Sow outdoors: Apr 28 to May 19
Sow outdoors: Apr 28 to May 19Plant for fall: Jul 14 to Aug 4
Sow outdoors: May 5 to Jun 16Plant for fall: Jul 28 to Aug 18
Start indoors: May 12 to May 19Transplant outside: Jun 23 to Jun 30Sow outdoors: Jun 16 to Jun 30
Start indoors: May 12 to May 19Sow outdoors: Jun 16 to Jun 30
Start indoors: May 12 to May 19Sow outdoors: Jun 16 to Jun 30
Start indoors: May 12 to May 19Transplant outside: Jun 23 to Jul 7
Sow outdoors: May 19 to Jun 16
Sow outdoors: May 19 to Jun 16
Sow outdoors: May 19 to Jun 9
Sow outdoors: May 26 to Jun 23
Sow outdoors: May 26 to Jun 16Plant for fall: Jul 14 to Aug 4
Sow outdoors: Jun 16 to Jul 7
Sow outdoors: Jun 16 to Jun 30
Transplant outside: Jun 23 to Jul 14
Plant for fall: Aug 25 to Sep 29
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Avon, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 17 – Mar 31 | May 12 – May 26 | — | — |
| Peppers | Mar 31 – Apr 14 | Jun 23 – Jul 7 | — | — |
| Eggplant | Mar 31 – Apr 14 | Jun 23 – Jul 7 | — | — |
| Tomatoes | Apr 14 – Apr 28 | Jun 16 – Jun 30 | — | — |
| Lettuce | Apr 14 – Apr 28 | May 19 – Jun 2 | May 12 – Jun 16 | Jul 14 – Aug 11 |
| Kale | Apr 14 – Apr 28 | May 12 – May 26 | May 12 – May 26 | Jun 30 – Jul 21 |
| Broccoli | Apr 14 – Apr 28 | May 26 – Jun 9 | — | — |
| Cabbage | Apr 14 – Apr 28 | May 19 – Jun 2 | — | — |
| Cauliflower | Apr 14 – Apr 28 | May 26 – Jun 9 | — | — |
| Okra | Apr 28 – May 12 | Jun 30 – Jul 14 | Jun 30 – Jul 14 | — |
| Basil | Apr 28 – May 12 | Jun 16 – Jun 30 | — | — |
| Peas | — | — | Apr 28 – May 19 | — |
| Spinach | — | — | Apr 28 – May 19 | Jul 14 – Aug 4 |
| Radishes | — | — | May 5 – Jun 16 | Jul 28 – Aug 18 |
| Cucumbers | May 12 – May 19 | Jun 23 – Jun 30 | Jun 16 – Jun 30 | — |
| Zucchini & Summer Squash | May 12 – May 19 | — | Jun 16 – Jun 30 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 91 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 12 – May 19 | — | Jun 16 – Jun 30 | — |
| Melons & Watermelon Warning: Your frost-free season is about 91 days, which is tight for melons & watermelon (85+ days). Choose early varieties and use transplants or row covers. | May 12 – May 19 | Jun 23 – Jul 7 | — | — |
| Carrots | — | — | May 19 – Jun 16 | — |
| Beets | — | — | May 19 – Jun 16 | — |
| Potatoes | — | — | May 19 – Jun 9 | — |
| Swiss Chard | — | — | May 26 – Jun 23 | — |
| Cilantro | — | — | May 26 – Jun 16 | Jul 14 – Aug 4 |
| Green Beans | — | — | Jun 16 – Jul 7 | — |
| Sweet Corn Warning: Your frost-free season is about 91 days, which is tight for sweet corn (80+ days). Choose early varieties and use transplants or row covers. | — | — | Jun 16 – Jun 30 | — |
| Sweet Potatoes Warning: Your frost-free season is about 91 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 23 – Jul 14 | — | — |
| Garlic | — | — | — | Aug 25 – Sep 29 |
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 Elliston, MT weather station, 13 km away (elevation 5,079 ft (1,548 m)).
Frost dates near Avon
- Garrison frost any month
- Elliston Jun 9 · Sep 8
- Deer Lodge frost any month
- Gold Creek frost any month
- Marysville Jun 4 · Sep 14
- Canyon Creek Jun 4 · Sep 14
- Helmville frost any month
- Fort Harrison May 9 · Sep 30
- Lincoln frost any month
- Basin Jun 7 · Sep 8
Frequently asked questions
When is the last frost in Avon, MT?
The median last spring frost in Avon, MT is June 9. There is still about a 10% chance of frost after June 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Avon, MT?
The median first fall frost is September 8, with about a 10% chance of frost before August 26.
How long is the growing season in Avon, MT?
About 91 days between the median last spring frost and first fall frost.
What planting zone is Avon, MT?
Avon, MT is in USDA hardiness zone 4b.