Frost dates for Thompson Falls, 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 7
typical year
Safe to plant
May 19
frost is over in 9 of 10 years
First fall frost
October 4
typical year
Growing season
150 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 9 – 23 | – |
| Spinach | – | Mar 26 – Apr 16 | Aug 9 – 23 |
| Lettuce | – | Apr 9 – 30 | Aug 9 – 23 |
| Radishes | – | Apr 9 – May 21 | Aug 23 – Sep 6 |
| Onions | – | Apr 9 – 23 | – |
| Potatoes | – | Apr 16 – 30 | – |
| Carrots | – | Apr 16 – May 7 | Jul 12 – 26 |
| Beets | – | Apr 9 – 23 | Jul 26 – Aug 9 |
| Kale | Feb 26 – Mar 12 | Apr 9 – 23 | Jul 26 – Aug 9 |
| Broccoli | Feb 26 – Mar 12 | Apr 23 – May 7 | Jul 26 – Aug 9 |
| Cabbage | Feb 12 – 26 | Apr 9 – 23 | Jul 26 – Aug 9 |
| Garlic | – | – | Aug 23 – Sep 13 |
| Warm-season crops | |||
| Tomatoes | Mar 24 – Apr 7 | May 19 – Jun 2 | – |
| Peppers | Mar 17 – 31 | May 26 – Jun 9 | – |
| Cucumbers | – | May 19 – Jun 9 | – |
| Zucchini | – | May 19 – Jun 16 | – |
| Pumpkins | – | May 19 – Jun 9 | – |
| Green beans | – | May 19 – Jul 26 | – |
| Sweet corn | – | May 19 – Jun 16 | – |
| Basil | Apr 14 – 28 | May 26 – Jun 2 | – |
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 19 | May 7 | April 25 |
| Fall frost before | September 21 | October 4 | October 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 April 22 (May 6 in a late year), and the first one in fall around October 18.
Towns that use these dates
This is the nearest NOAA station with frost records for 1 town.
Thompson Falls
Where these dates come from
NOAA weather station THOMPSON FALLS PH, MT US (USC00248211), 1991–2020 climate normals. It's the nearest station for 1 zip code, all within 6 miles:
59873
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.