Median last frost from May 7 to Jun 9 across Montana
NOAA stations
210
Median last frost, Missoula
May 16
Passed in 9 of 10 years
Jun 1
Last frost
Last spring frost dates in Montana
Billings on the Yellowstone reaches its median last frost around May 4, Havre, Missoula and Wolf Point in mid May, and Bozeman in the Gallatin Valley around May 26.
Three dates per station from the NOAA 1991 to 2020 normals. The median is the date half of springs run past. The last column is the date the last 32°F night has passed by in 9 years out of 10, the one to hold tender transplants for.
Station
Elevation
Early (1 in 10 years later than this)
Median last frost
Passed in 9 of 10 years
Median first fall frost
BillingsBillings Logan Intl Airport, USW00024033
3,581 ft
Apr 20
May 4
May 18
Oct 7
Havre City County AirportHavre City County Airport, USW00094012
2,585 ft
May 3
May 15
May 27
Sep 23
MissoulaMissoula Intl Airport, USW00024153
3,192 ft
May 3
May 16
Jun 1
Sep 26
Wolf Point Intl AirportWolf Point Intl Airport, USW00094017
1,986 ft
May 5
May 16
May 29
Sep 20
BozemanBozeman Montana State University, USC00241044
4,913 ft
May 9
May 26
Jun 14
Sep 22
Crop chart
When to start seeds in Montana, spring 2027
Counted back from the median last frost at Missoula, May 16. Pick another station to redraw the chart for it.
Start indoorsHarden offSet outSow outdoorsMedian last frostLast freeze passed in 9 of 10 years
Every crop, counted from a median last frost of May 16
Crop
Start indoors
Set out
Sow outdoors
Frost class
Tomato
Mar 28 to Apr 11
May 23 to May 30
Tender, very tender
Pepper
Mar 21 to Apr 4
May 30 to Jun 6
Tender, very tender
Eggplant
Mar 21 to Apr 4
May 30 to Jun 6
Tender, very tender
Basil
Apr 4 to Apr 18
May 30 to Jun 6
Tender
Celery
Feb 21 to Mar 7
May 16 to May 23
Tender
Cucumber
Apr 25 to May 2
May 23 to May 30
May 16 to May 23
Tender
Summer squash
May 2 to May 9
May 30 to Jun 6
May 16 to May 23
Tender
Winter squash
May 2 to May 9
May 30 to Jun 6
May 30 to Jun 6
Tender, very tender
Pumpkin
May 2 to May 9
May 30 to Jun 6
May 30 to Jun 6
Tender, very tender
Melon (cantaloupe)
May 2 to May 9
May 30 to Jun 6
Tender, very tender
Watermelon
Apr 25 to May 9
May 30 to Jun 6
Tender, very tender
Onion (from seed)
Feb 7 to Feb 21
Apr 18 to Apr 25
Hardy
Leek
Feb 7 to Feb 21
Apr 18 to Apr 25
Hardy
Parsley
Feb 14 to Feb 21
Apr 25 to May 2
Half-hardy
Broccoli
Mar 7 to Mar 21
Apr 18 to May 2
Hardy
Brussels sprouts
Mar 7 to Mar 21
Apr 18 to May 2
Hardy
Cabbage
Mar 7 to Mar 21
Apr 18 to Apr 25
Hardy
Cauliflower
Mar 21 to Apr 4
May 2 to May 9
Half-hardy
Kale
Mar 7 to Mar 21
Apr 18 to Apr 25
Hardy
Lettuce
Mar 14 to Mar 21
Apr 18 to Apr 25
Hardy
Swiss chard
Mar 21 to Apr 4
May 2 to May 9
Apr 18 to Apr 25
Half-hardy
Spinach
Feb 21 to Mar 7
Apr 4 to Apr 25
Apr 18 to May 2
Hardy
Peas
Apr 18 to May 2
Hardy
Radish
Apr 18 to May 2
Hardy
Carrot
May 2 to May 16
Half-hardy
Beet
May 2 to May 16
Half-hardy
Beans
May 16 to May 23
Tender
Sweet corn
May 16 to May 23
Tender
Tomato seedlings at the seed leaf stage, one to a pot. The University of Minnesota Extension holds off on fertilizer until a seedling has several sets of true leaves, then feeds at quarter strength once a week.“Tomato Seedlings (49768696597)” by Amanda Slater from Coventry, West Midlands, UK, CC BY-SA 2.0
Setting out a tomato in June at a community garden. Tender crops go out after the last frost, and after a week or two of hardening off outdoors. “Volunteer planting heirloom tomato (4704185147)”, Pacific Southwest Region 5, Public domain
Seed starting questions for Montana
Count back from the median last frost where you garden. At Missoula (Missoula Intl Airport) that date is May 16, so for spring 2027 onions start indoors Feb 7 to Feb 21, peppers Mar 21 to Apr 4 and tomatoes Mar 28 to Apr 11. Across Montana's 210 NOAA stations the median last frost runs from May 7 to Jun 9 for the middle 90 percent, so a garden near Tizer Gardens starts later than one near Norris Madison Power House.
It depends on the station. The earliest median last spring freeze in Montana is April 30 at Norris Madison Power House; the latest is June 18 at Tizer Gardens. A median is a coin flip: at Missoula the last 32°F freeze comes after May 16 in half of years, and has passed by June 1 in 9 of 10 years (NOAA 1991 to 2020 normals).
UNH Extension sets tomatoes out 1 to 2 weeks after the last frost, which at Missoula is May 23 to May 30 in 2027. Tomatoes are frost tender, so the date to watch is June 1, when 9 of 10 springs at Missoula have had their last 32°F night. Hardening off starts two weeks before setting out (May 9 to May 23).
Montana State University Extension's Can I Grow That Here? Vegetable Seed and Transplant Schedules for Garden or Container puts it this way: "Then, with the aid of a calendar, calculate from those dates the spring planting dates for your area and the transplant starting dates." The guide is linked below with the date it was read (September 21, 2026).
UNH Extension gives 8 to 10 weeks from seed to transplant for both, and sets peppers out 2 weeks after the last frost and eggplant 2 to 3 weeks after, so the sowing date is 6 to 8 weeks before the median last frost. At Missoula that is Mar 21 to Apr 4 for peppers.
About two weeks. University of Missouri Extension: "Hardening should be started about two weeks before planting in the garden." University of Minnesota Extension adds that seedlings should go out on a cloudy day or in the late afternoon.
Billings on the Yellowstone reaches its median last frost around May 4, Havre, Missoula and Wolf Point in mid May, and Bozeman in the Gallatin Valley around May 26. Each station carries its own dates: Billings May 4 and Bozeman May 26 at the median.
