Frost dates for Hungry Horse Dam, 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
May 9
typical year
Safe to plant
May 30
frost is over in 9 of 10 years
First fall frost
October 1
typical year
Growing season
141 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 | – | Apr 11 – 25 | – |
| Spinach | – | Mar 28 – Apr 18 | Aug 6 – 20 |
| Lettuce | – | Apr 11 – May 2 | Aug 6 – 20 |
| Radishes | – | Apr 11 – May 23 | Aug 20 – Sep 3 |
| Onions | – | Apr 11 – 25 | – |
| Potatoes | – | Apr 18 – May 2 | – |
| Carrots | – | Apr 18 – May 9 | Jul 9 – 23 |
| Beets | – | Apr 11 – 25 | Jul 23 – Aug 6 |
| Kale | Feb 28 – Mar 14 | Apr 11 – 25 | Jul 23 – Aug 6 |
| Broccoli | Feb 28 – Mar 14 | Apr 25 – May 9 | Jul 23 – Aug 6 |
| Cabbage | Feb 14 – 28 | Apr 11 – 25 | Jul 23 – Aug 6 |
| Garlic | – | – | Aug 20 – Sep 10 |
| Warm-season crops | |||
| Tomatoes | Apr 4 – 18 | May 30 – Jun 13 | – |
| Peppers | Mar 28 – Apr 11 | Jun 6 – 20 | – |
| Cucumbers | – | May 30 – Jun 20 | – |
| Zucchini | – | May 30 – Jun 27 | – |
| Pumpkins | – | May 30 – Jun 20 | – |
| Green beans | – | May 30 – Jul 23 | – |
| Sweet corn | – | May 30 – Jun 27 | – |
| Basil | Apr 25 – May 9 | Jun 6 – 13 | – |
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 | May 30 | May 9 | April 25 |
| Fall frost before | September 13 | October 1 | October 17 |
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 April 27 (May 14 in a late year), and the first one in fall around October 14.
Where these dates come from
NOAA weather station HUNGRY HORSE DAM, MT US (USC00244328), 1991–2020 climate normals. It's the nearest station for 3 zip codes, all within 17 miles:
59916, 59919, 59926
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.