Frost dates for Butte-Silver Bow, MT
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
June 13
typical year
Safe to plant
July 1
frost is over in 9 of 10 years
First fall frost
September 5
typical year
Growing season
83 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | May 16 – 30 | – |
| Spinach | – | May 2 – 23 | Jul 11 – 25 |
| Lettuce | – | May 16 – Jun 6 | Jul 11 – 25 |
| Radishes | – | May 16 – Jun 27 | Jul 25 – Aug 8 |
| Onions | – | May 16 – 30 | – |
| Potatoes | Season usually too short. Try a quick variety or row covers. | ||
| Carrots | – | May 23 – Jun 13 | Jun 13 – 27 |
| Beets | – | May 16 – 30 | Jun 27 – Jul 11 |
| Kale | Apr 4 – 18 | May 16 – 30 | Jun 27 – Jul 11 |
| Broccoli | Apr 4 – 18 | May 30 – Jun 13 | Jun 27 – Jul 11 |
| Cabbage | Mar 21 – Apr 4 | May 16 – 30 | Jun 27 – Jul 11 |
| Garlic | – | – | Jul 25 – Aug 15 |
| Warm-season crops | |||
| Tomatoes | Season usually too short. Try a quick variety or row covers. | ||
| Peppers | Season usually too short. Try a quick variety or row covers. | ||
| Cucumbers | – | Jul 1 – 22 | – |
| Zucchini | – | Jul 1 – 29 | – |
| Pumpkins | Season usually too short. Try a quick variety or row covers. | ||
| Green beans | Season usually too short. Try a quick variety or row covers. | ||
| Sweet corn | Season usually too short. Try a quick variety or row covers. | ||
| Basil | May 27 – Jun 10 | Jul 8 – 15 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | July 1 | June 13 | May 27 |
| Fall frost before | August 24 | September 5 | September 19 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around May 21 (June 10 in a late year), and the first one in fall around September 17.
Towns that use these dates
This is the nearest NOAA station with frost records for 3 towns.
Butte-Silver Bow, Whitehall, Walkerville
Where these dates come from
NOAA weather station BUTTE BERT MOONEY AP, MT US (USW00024135), 1991–2020 climate normals. It's the nearest station for 4 zip codes, all within 18 miles:
59701, 59748, 59750, 59759
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.