Columbus, MT frost dates
Last spring frostMay 27median date
First fall frostSep 14median date
Growing season110 daysfrost-free
Hardiness zone5aZone 5a
How Columbus compares
- In 8 years out of 10, the last spring frost in Columbus falls between May 14 and June 12, a 29-day window. The first fall frost falls between September 1 and September 28.
- The median last frost is 8 days later than the Montana median of May 19.
- Its 110-day growing season is longer than 21% of the 325 Montana places with a regular frost season (state median 125 days).
- The last frost is 24 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 183 nights a year at or below 32°F.
- Compared with Billings, MT, 61 km away, the last frost here is 23 days later than there and the growing season is 46 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 14 |
| 50% (median) | May 27 |
| 10% (safe for tender plants) | June 12 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 1 |
| 50% (median) | September 14 |
| 90% (late) | September 28 |
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 Columbus, MT
Columbus, MT frost dates — last frost May 27, first frost Sep 14, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 29 to May 13
Start indoors: Mar 18 to Apr 1Transplant outside: Jun 10 to Jun 24
Start indoors: Mar 18 to Apr 1Transplant outside: Jun 10 to Jun 24
Start indoors: Apr 1 to Apr 15Transplant outside: Jun 3 to Jun 17
Start indoors: Apr 1 to Apr 15Transplant outside: May 6 to May 20Sow outdoors: Apr 29 to Jun 3Plant for fall: Jul 20 to Aug 17
Start indoors: Apr 1 to Apr 15Transplant outside: Apr 29 to May 13Sow outdoors: Apr 29 to May 13Plant for fall: Jul 6 to Jul 27
Start indoors: Apr 1 to Apr 15Transplant outside: May 13 to May 27
Start indoors: Apr 1 to Apr 15Transplant outside: May 6 to May 20
Start indoors: Apr 1 to Apr 15Transplant outside: May 13 to May 27
Start indoors: Apr 15 to Apr 29Transplant outside: Jun 17 to Jul 1Sow outdoors: Jun 17 to Jul 1
Start indoors: Apr 15 to Apr 29Transplant outside: Jun 3 to Jun 17
Sow outdoors: Apr 15 to May 6Plant for fall: Jun 22 to Jul 13
Sow outdoors: Apr 15 to May 6Plant for fall: Jul 20 to Aug 10
Sow outdoors: Apr 22 to Jun 3Plant for fall: Aug 3 to Aug 24
Start indoors: Apr 29 to May 6Transplant outside: Jun 10 to Jun 17Sow outdoors: Jun 3 to Jun 17
Start indoors: Apr 29 to May 6Sow outdoors: Jun 3 to Jun 17Plant for fall: Jul 6 to Jul 20
Start indoors: Apr 29 to May 6Sow outdoors: Jun 3 to Jun 17
Start indoors: Apr 29 to May 6Transplant outside: Jun 10 to Jun 24
Sow outdoors: May 6 to Jun 3Plant for fall: Jun 22 to Jul 6
Sow outdoors: May 6 to Jun 3Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 6 to May 27
Sow outdoors: May 13 to Jun 10Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 13 to Jun 3Plant for fall: Jul 20 to Aug 10
Sow outdoors: Jun 3 to Jun 24
Sow outdoors: Jun 3 to Jun 17
Transplant outside: Jun 10 to Jul 1
Plant for fall: Aug 31 to Oct 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Columbus, MT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 4 – Mar 18 | Apr 29 – May 13 | — | — |
| Peppers | Mar 18 – Apr 1 | Jun 10 – Jun 24 | — | — |
| Eggplant | Mar 18 – Apr 1 | Jun 10 – Jun 24 | — | — |
| Tomatoes | Apr 1 – Apr 15 | Jun 3 – Jun 17 | — | — |
| Lettuce | Apr 1 – Apr 15 | May 6 – May 20 | Apr 29 – Jun 3 | Jul 20 – Aug 17 |
| Kale | Apr 1 – Apr 15 | Apr 29 – May 13 | Apr 29 – May 13 | Jul 6 – Jul 27 |
| Broccoli | Apr 1 – Apr 15 | May 13 – May 27 | — | — |
| Cabbage | Apr 1 – Apr 15 | May 6 – May 20 | — | — |
| Cauliflower | Apr 1 – Apr 15 | May 13 – May 27 | — | — |
| Okra | Apr 15 – Apr 29 | Jun 17 – Jul 1 | Jun 17 – Jul 1 | — |
| Basil | Apr 15 – Apr 29 | Jun 3 – Jun 17 | — | — |
| Peas | — | — | Apr 15 – May 6 | Jun 22 – Jul 13 |
| Spinach | — | — | Apr 15 – May 6 | Jul 20 – Aug 10 |
| Radishes | — | — | Apr 22 – Jun 3 | Aug 3 – Aug 24 |
| Cucumbers | Apr 29 – May 6 | Jun 10 – Jun 17 | Jun 3 – Jun 17 | — |
| Zucchini & Summer Squash | Apr 29 – May 6 | — | Jun 3 – Jun 17 | Jul 6 – Jul 20 |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 110 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | Apr 29 – May 6 | — | Jun 3 – Jun 17 | — |
| Melons & Watermelon | Apr 29 – May 6 | Jun 10 – Jun 24 | — | — |
| Carrots | — | — | May 6 – Jun 3 | Jun 22 – Jul 6 |
| Beets | — | — | May 6 – Jun 3 | Jul 6 – Jul 20 |
| Potatoes | — | — | May 6 – May 27 | — |
| Swiss Chard | — | — | May 13 – Jun 10 | Jul 6 – Jul 20 |
| Cilantro | — | — | May 13 – Jun 3 | Jul 20 – Aug 10 |
| Green Beans | — | — | Jun 3 – Jun 24 | — |
| Sweet Corn | — | — | Jun 3 – Jun 17 | — |
| Sweet Potatoes Warning: Your frost-free season is about 110 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 10 – Jul 1 | — | — |
| Garlic | — | — | — | Aug 31 – Oct 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 Columbus, MT weather station, 2 km away (elevation 3,602 ft (1,098 m)).
Frost dates near Columbus
- Absarokee May 27 · Sep 14
- Boyd May 29 · Sep 15
- Reed Point May 27 · Sep 14
- Joliet May 29 · Sep 15
- Park City May 29 · Sep 15
- Roberts May 29 · Sep 15
- Molt May 24 · Sep 21
- Fishtail Jun 1 · Sep 11
- Edgar May 29 · Sep 15
- Fromberg May 14 · Sep 24
Frequently asked questions
When is the last frost in Columbus, MT?
The median last spring frost in Columbus, MT is May 27. There is still about a 10% chance of frost after June 12, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Columbus, MT?
The median first fall frost is September 14, with about a 10% chance of frost before September 1.
How long is the growing season in Columbus, MT?
About 110 days between the median last spring frost and first fall frost.
What planting zone is Columbus, MT?
Columbus, MT is in USDA hardiness zone 5a.