Frost Report

All states Montana

Frost dates for Belt, 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 22

typical year

Safe to plant

June 9

frost is over in 9 of 10 years

First fall frost

September 23

typical year

Growing season

123 days

frost-free, typical year

When to plant

Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.

CropStart indoorsPlant outsideFall planting
Cool-season crops
Peas – Apr 24 – May 8 –
Spinach – Apr 10 – May 1 Jul 29 – Aug 12
Lettuce – Apr 24 – May 15 Jul 29 – Aug 12
Radishes – Apr 24 – Jun 5 Aug 12 – 26
Onions – Apr 24 – May 8 –
Potatoes – May 1 – 15 –
Carrots – May 1 – 22 Jul 1 – 15
Beets – Apr 24 – May 8 Jul 15 – 29
Kale Mar 13 – 27 Apr 24 – May 8 Jul 15 – 29
Broccoli Mar 13 – 27 May 8 – 22 Jul 15 – 29
Cabbage Feb 27 – Mar 13 Apr 24 – May 8 Jul 15 – 29
Garlic – – Aug 12 – Sep 2
Warm-season crops
Tomatoes Apr 14 – 28 Jun 9 – 23 –
Peppers Apr 7 – 21 Jun 16 – 30 –
Cucumbers – Jun 9 – 30 –
Zucchini – Jun 9 – Jul 7 –
Pumpkins – Jun 9 – 30 –
Green beans – Jun 9 – Jul 15 –
Sweet corn – Jun 9 – Jul 7 –
Basil May 5 – 19 Jun 16 – 23 –

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 10Half of years9 years in 10
Spring frost after June 9May 22May 7
Fall frost before September 7September 23October 6

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 7 (May 22 in a late year), and the first one in fall around October 2.

Towns that use these dates

This is the nearest NOAA station with frost records for 1 town.

Belt

Where these dates come from

NOAA weather station RAYNESFORD 2 NNW, MT US (USC00246902), 1991–2020 climate normals. It's the nearest station for 4 zip codes, all within 16 miles:

59412, 59447, 59469, 59480

Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.