Fromberg, MT frost dates
Last spring frostMay 14median date
First fall frostSep 24median date
Growing season133 daysfrost-free
Hardiness zone5aZone 5a
How Fromberg compares
- In 8 years out of 10, the last spring frost in Fromberg falls between May 2 and May 30, a 28-day window. The first fall frost falls between September 7 and October 7.
- The median last frost is 5 days earlier than the Montana median of May 19.
- Its 133-day growing season is longer than 66% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 11 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 179 nights a year at or below 32°F.
- Compared with Billings, MT, 53 km away, the last frost here is 10 days later than there and the growing season is 23 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 2 |
| 50% (median) | May 14 |
| 10% (safe for tender plants) | May 30 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 7 |
| 50% (median) | September 24 |
| 90% (late) | October 7 |
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 Fromberg, MT
Fromberg, MT frost dates — last frost May 14, first frost Sep 24, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 19 to Mar 5Transplant outside: Apr 16 to Apr 30
Start indoors: Mar 5 to Mar 19Transplant outside: May 28 to Jun 11
Start indoors: Mar 5 to Mar 19Transplant outside: May 28 to Jun 11
Start indoors: Mar 19 to Apr 2Transplant outside: May 21 to Jun 4
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 23 to May 7Sow outdoors: Apr 16 to May 21Plant for fall: Jul 30 to Aug 27
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 16 to Apr 30Sow outdoors: Apr 16 to Apr 30Plant for fall: Jul 16 to Aug 6
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 30 to May 14Plant for fall: Jun 18 to Jul 9
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 23 to May 7Plant for fall: Jun 18 to Jul 9
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 30 to May 14Plant for fall: Jun 18 to Jul 9
Start indoors: Apr 2 to Apr 16Transplant outside: Jun 4 to Jun 18Sow outdoors: Jun 4 to Jun 18
Start indoors: Apr 2 to Apr 16Transplant outside: May 21 to Jun 4
Sow outdoors: Apr 2 to Apr 23Plant for fall: Jul 2 to Jul 23
Sow outdoors: Apr 2 to Apr 23Plant for fall: Jul 30 to Aug 20
Sow outdoors: Apr 9 to May 21Plant for fall: Aug 13 to Sep 3
Start indoors: Apr 16 to Apr 23Transplant outside: May 28 to Jun 4Sow outdoors: May 21 to Jun 4Plant for fall: Jul 9 to Jul 23
Start indoors: Apr 16 to Apr 23Sow outdoors: May 21 to Jun 4Plant for fall: Jul 16 to Jul 30
Start indoors: Apr 16 to Apr 23Sow outdoors: May 21 to Jun 4
Start indoors: Apr 16 to Apr 23Transplant outside: May 28 to Jun 11
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 2 to Jul 16
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 16 to Jul 30
Sow outdoors: Apr 23 to May 14
Sow outdoors: Apr 30 to May 28Plant for fall: Jul 16 to Jul 30
Sow outdoors: Apr 30 to May 21Plant for fall: Jul 30 to Aug 20
Sow outdoors: May 21 to Jun 11Plant for fall: Jul 9 to Jul 23
Sow outdoors: May 21 to Jun 4
Transplant outside: May 28 to Jun 18
Plant for fall: Sep 10 to Oct 15
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Fromberg, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 19 – Mar 5 | Apr 16 – Apr 30 | — | — |
| Peppers | Mar 5 – Mar 19 | May 28 – Jun 11 | — | — |
| Eggplant | Mar 5 – Mar 19 | May 28 – Jun 11 | — | — |
| Tomatoes | Mar 19 – Apr 2 | May 21 – Jun 4 | — | — |
| Lettuce | Mar 19 – Apr 2 | Apr 23 – May 7 | Apr 16 – May 21 | Jul 30 – Aug 27 |
| Kale | Mar 19 – Apr 2 | Apr 16 – Apr 30 | Apr 16 – Apr 30 | Jul 16 – Aug 6 |
| Broccoli | Mar 19 – Apr 2 | Apr 30 – May 14 | — | Jun 18 – Jul 9 |
| Cabbage | Mar 19 – Apr 2 | Apr 23 – May 7 | — | Jun 18 – Jul 9 |
| Cauliflower | Mar 19 – Apr 2 | Apr 30 – May 14 | — | Jun 18 – Jul 9 |
| Okra | Apr 2 – Apr 16 | Jun 4 – Jun 18 | Jun 4 – Jun 18 | — |
| Basil | Apr 2 – Apr 16 | May 21 – Jun 4 | — | — |
| Peas | — | — | Apr 2 – Apr 23 | Jul 2 – Jul 23 |
| Spinach | — | — | Apr 2 – Apr 23 | Jul 30 – Aug 20 |
| Radishes | — | — | Apr 9 – May 21 | Aug 13 – Sep 3 |
| Cucumbers | Apr 16 – Apr 23 | May 28 – Jun 4 | May 21 – Jun 4 | Jul 9 – Jul 23 |
| Zucchini & Summer Squash | Apr 16 – Apr 23 | — | May 21 – Jun 4 | Jul 16 – Jul 30 |
| Winter Squash & Pumpkins | Apr 16 – Apr 23 | — | May 21 – Jun 4 | — |
| Melons & Watermelon | Apr 16 – Apr 23 | May 28 – Jun 11 | — | — |
| Carrots | — | — | Apr 23 – May 21 | Jul 2 – Jul 16 |
| Beets | — | — | Apr 23 – May 21 | Jul 16 – Jul 30 |
| Potatoes | — | — | Apr 23 – May 14 | — |
| Swiss Chard | — | — | Apr 30 – May 28 | Jul 16 – Jul 30 |
| Cilantro | — | — | Apr 30 – May 21 | Jul 30 – Aug 20 |
| Green Beans | — | — | May 21 – Jun 11 | Jul 9 – Jul 23 |
| Sweet Corn | — | — | May 21 – Jun 4 | — |
| Sweet Potatoes | — | May 28 – Jun 18 | — | — |
| Garlic | — | — | — | Sep 10 – Oct 15 |
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 Bridger 2 N, MT weather station, 9 km away (elevation 3,583 ft (1,092 m)).
Frost dates near Fromberg
- Edgar May 29 · Sep 15
- Joliet May 29 · Sep 15
- Bridger May 14 · Sep 24
- Boyd May 29 · Sep 15
- Roberts May 29 · Sep 15
- Park City May 29 · Sep 15
- Pryor May 14 · Sep 24
- Laurel May 5 · Oct 3
- Bearcreek Jun 3 · Sep 19
- Red Lodge Jun 3 · Sep 19
Frequently asked questions
When is the last frost in Fromberg, MT?
The median last spring frost in Fromberg, MT is May 14. There is still about a 10% chance of frost after May 30, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Fromberg, MT?
The median first fall frost is September 24, with about a 10% chance of frost before September 7.
How long is the growing season in Fromberg, MT?
About 133 days between the median last spring frost and first fall frost.
What planting zone is Fromberg, MT?
Fromberg, MT is in USDA hardiness zone 5a.