Belfry, MT frost dates
Last spring frostMay 18median date
First fall frostSep 22median date
Growing season127 daysfrost-free
Hardiness zone5aZone 5a
How Belfry compares
- In 8 years out of 10, the last spring frost in Belfry falls between May 6 and June 4, a 29-day window. The first fall frost falls between September 8 and October 4.
- The median last frost is 1 day earlier than the Montana median of May 19.
- Its 127-day growing season is longer than 54% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 15 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 191 nights a year at or below 32°F.
- Compared with Billings, MT, 94 km away, the last frost here is 14 days later than there and the growing season is 29 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 6 |
| 50% (median) | May 18 |
| 10% (safe for tender plants) | June 4 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 8 |
| 50% (median) | September 22 |
| 90% (late) | October 4 |
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 Belfry, MT
Belfry, MT frost dates — last frost May 18, first frost Sep 22, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Feb 23 to Mar 9Transplant outside: Apr 20 to May 4
Start indoors: Mar 9 to Mar 23Transplant outside: Jun 1 to Jun 15
Start indoors: Mar 9 to Mar 23Transplant outside: Jun 1 to Jun 15
Start indoors: Mar 23 to Apr 6Transplant outside: May 25 to Jun 8
Start indoors: Mar 23 to Apr 6Transplant outside: Apr 27 to May 11Sow outdoors: Apr 20 to May 25Plant for fall: Jul 28 to Aug 25
Start indoors: Mar 23 to Apr 6Transplant outside: Apr 20 to May 4Sow outdoors: Apr 20 to May 4Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 23 to Apr 6Transplant outside: May 4 to May 18Plant for fall: Jun 16 to Jul 7
Start indoors: Mar 23 to Apr 6Transplant outside: Apr 27 to May 11Plant for fall: Jun 16 to Jul 7
Start indoors: Mar 23 to Apr 6Transplant outside: May 4 to May 18Plant for fall: Jun 16 to Jul 7
Start indoors: Apr 6 to Apr 20Transplant outside: Jun 8 to Jun 22Sow outdoors: Jun 8 to Jun 22
Start indoors: Apr 6 to Apr 20Transplant outside: May 25 to Jun 8
Sow outdoors: Apr 6 to Apr 27Plant for fall: Jun 30 to Jul 21
Sow outdoors: Apr 6 to Apr 27Plant for fall: Jul 28 to Aug 18
Sow outdoors: Apr 13 to May 25Plant for fall: Aug 11 to Sep 1
Start indoors: Apr 20 to Apr 27Transplant outside: Jun 1 to Jun 8Sow outdoors: May 25 to Jun 8Plant for fall: Jul 7 to Jul 21
Start indoors: Apr 20 to Apr 27Sow outdoors: May 25 to Jun 8Plant for fall: Jul 14 to Jul 28
Start indoors: Apr 20 to Apr 27Sow outdoors: May 25 to Jun 8
Start indoors: Apr 20 to Apr 27Transplant outside: Jun 1 to Jun 15
Sow outdoors: Apr 27 to May 25Plant for fall: Jun 30 to Jul 14
Sow outdoors: Apr 27 to May 25Plant for fall: Jul 14 to Jul 28
Sow outdoors: Apr 27 to May 18
Sow outdoors: May 4 to Jun 1Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 4 to May 25Plant for fall: Jul 28 to Aug 18
Sow outdoors: May 25 to Jun 15Plant for fall: Jul 7 to Jul 21
Sow outdoors: May 25 to Jun 8
Transplant outside: Jun 1 to Jun 22
Plant for fall: Sep 8 to Oct 13
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Belfry, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 23 – Mar 9 | Apr 20 – May 4 | — | — |
| Peppers | Mar 9 – Mar 23 | Jun 1 – Jun 15 | — | — |
| Eggplant | Mar 9 – Mar 23 | Jun 1 – Jun 15 | — | — |
| Tomatoes | Mar 23 – Apr 6 | May 25 – Jun 8 | — | — |
| Lettuce | Mar 23 – Apr 6 | Apr 27 – May 11 | Apr 20 – May 25 | Jul 28 – Aug 25 |
| Kale | Mar 23 – Apr 6 | Apr 20 – May 4 | Apr 20 – May 4 | Jul 14 – Aug 4 |
| Broccoli | Mar 23 – Apr 6 | May 4 – May 18 | — | Jun 16 – Jul 7 |
| Cabbage | Mar 23 – Apr 6 | Apr 27 – May 11 | — | Jun 16 – Jul 7 |
| Cauliflower | Mar 23 – Apr 6 | May 4 – May 18 | — | Jun 16 – Jul 7 |
| Okra | Apr 6 – Apr 20 | Jun 8 – Jun 22 | Jun 8 – Jun 22 | — |
| Basil | Apr 6 – Apr 20 | May 25 – Jun 8 | — | — |
| Peas | — | — | Apr 6 – Apr 27 | Jun 30 – Jul 21 |
| Spinach | — | — | Apr 6 – Apr 27 | Jul 28 – Aug 18 |
| Radishes | — | — | Apr 13 – May 25 | Aug 11 – Sep 1 |
| Cucumbers | Apr 20 – Apr 27 | Jun 1 – Jun 8 | May 25 – Jun 8 | Jul 7 – Jul 21 |
| Zucchini & Summer Squash | Apr 20 – Apr 27 | — | May 25 – Jun 8 | Jul 14 – Jul 28 |
| Winter Squash & Pumpkins | Apr 20 – Apr 27 | — | May 25 – Jun 8 | — |
| Melons & Watermelon | Apr 20 – Apr 27 | Jun 1 – Jun 15 | — | — |
| Carrots | — | — | Apr 27 – May 25 | Jun 30 – Jul 14 |
| Beets | — | — | Apr 27 – May 25 | Jul 14 – Jul 28 |
| Potatoes | — | — | Apr 27 – May 18 | — |
| Swiss Chard | — | — | May 4 – Jun 1 | Jul 14 – Jul 28 |
| Cilantro | — | — | May 4 – May 25 | Jul 28 – Aug 18 |
| Green Beans | — | — | May 25 – Jun 15 | Jul 7 – Jul 21 |
| Sweet Corn | — | — | May 25 – Jun 8 | — |
| Sweet Potatoes | — | Jun 1 – Jun 22 | — | — |
| Garlic | — | — | — | Sep 8 – Oct 13 |
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 Clark 3ne, WY weather station, 13 km away (elevation 4,117 ft (1,255 m)).
Frost dates near Belfry
- Bearcreek Jun 3 · Sep 19
- Red Lodge Jun 3 · Sep 19
- Bridger May 14 · Sep 24
- Roberts May 29 · Sep 15
- Fromberg May 14 · Sep 24
- Roscoe Jun 5 · Sep 14
- Boyd May 29 · Sep 15
- Edgar May 29 · Sep 15
- Joliet May 29 · Sep 15
- Fishtail Jun 1 · Sep 11
Frequently asked questions
When is the last frost in Belfry, MT?
The median last spring frost in Belfry, MT is May 18. There is still about a 10% chance of frost after June 4, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Belfry, MT?
The median first fall frost is September 22, with about a 10% chance of frost before September 8.
How long is the growing season in Belfry, MT?
About 127 days between the median last spring frost and first fall frost.
What planting zone is Belfry, MT?
Belfry, MT is in USDA hardiness zone 5a.