When is the last frost in Missoula, MT?

The average last spring frost (50% probability of 32°F) in Missoula is around May 10, based on NOAA/NCEI 1991–2020 normals at the Missoula 2 Ne, MT station (3.6 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Missoula?

The average first fall frost in Missoula, MT is around October 1, giving roughly a 143-day frost-free growing season.

What planting zone is Missoula, MT?

Missoula is in USDA plant hardiness zone 5b (average annual extreme minimum temperature -15 to -10°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Missoula?

In Missoula, MT the warmest month is July (avg high 85.1°F) and the coldest is December (avg low 19.6°F). It averages about 17.4″ of precipitation a year and 50.2″ of snow.

Home › Montana › Missoula

Missoula, MT Planting Calendar & Frost Dates

USDA hardiness zone 5b · ZIP 59801 · elevation 1042′ · NOAA & USDA data

Missoula is in USDA hardiness zone 5b (winters can dip to -15 to -10°F), with a growing season of about 143 days between the average last spring frost (May 10) and first fall frost (October 1). The warmest month is July (avg high 85.1°F); the coldest is December (avg low 19.6°F). It averages 17.4″ of precipitation a year and 50.2″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp -15 to -10°F

Last spring frost

May 10

avg (50% prob, 32°F)

First fall frost

October 1

avg (50% prob, 32°F)

Growing season

143 days

frost-free window

Warmest month

July

avg high 85.1°F

Month-by-month typical weather in Missoula

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Missoula 2 Ne, MT (3.6 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	34.1	19.8	27	1.2	12.5
February	39	21.9	30.5	1.1	7.9
March	49.1	27.4	38.3	1.2	7.4
April	56.8	33	44.9	1.7	1.4
May	66.5	40.8	53.6	2.3	0.3
June	73.4	46.9	60.1	2.6	0.2
July	85.1	52.2	68.7	1	0
August	84	51	67.5	1	0
September	73.1	43.6	58.3	1.1	0
October	56.5	33.7	45.1	1.4	0.7
November	41.2	26.2	33.7	1.4	6.9
December	32.9	19.6	26.2	1.4	12.9

What to plant when in Missoula

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 29 · Transplant out: May 17
Peppers	warm	Start seeds indoors: March 15 · Transplant out: May 24
Cucumbers	warm	Direct sow: May 17
Zucchini / squash	warm	Direct sow: May 17
Bush beans	warm	Direct sow: May 17
Sweet corn	warm	Direct sow: May 17
Basil	warm	Transplant out: May 17
Peas	cool	Sow (spring): April 5 · Sow (fall): August 6
Spinach	cool	Sow (spring): March 29 · Sow (fall): August 6
Lettuce	cool	Sow (spring): April 12 · Sow (fall): August 6
Kale	cool	Transplant (spring): April 19 · Sow (fall): July 23
Broccoli	cool	Transplant (spring): April 26
Carrots	cool	Sow (spring): April 19 · Sow (fall): July 23
Onions	cool	Transplant (spring): April 12
Potatoes	cool	Plant seed potatoes: April 26
Radishes	cool	Sow (spring): April 12 · Sow (fall): August 20

Dates are computed from Missoula's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Montana

Great Falls, MT Bozeman, MT Billings, MT

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Missoula 2 Ne, MT, 3.6 mi (confidence: high). Monthly weather normals: Missoula 2 Ne, MT, 3.6 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.