Missoula 6 NW Wfo, MT Frost Dates & Growing Season

The two dates every Missoula 6 NW Wfo garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
May 6
~50% chance of frost after
First fall frost
Oct 4
~50% chance of frost before
Growing season
151 days
frost-free stretch
USDA zone
≈ 6b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 24 May 6 May 19
First fall frost Oct 16 Oct 4 Sep 23
Hard freeze (28°F), median last Apr 23 · first Oct 15

Computed from NOAA 1991–2020 climate normals at the MISSOULA 6 NW WFO station. "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Missoula 6 NW Wfo

Computed from Missoula 6 NW Wfo's own frost dates. Click any crop for the full zone-6 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Mar 11 – Mar 25 May 13 – May 20
🫑 Peppers Feb 25 – Mar 11 May 20 – May 27
🥬 Lettuce Mar 25 – Apr 8 Apr 8 – Apr 22 Apr 8 – May 6
🫛 Peas Mar 25 – Apr 8
🥕 Carrots Apr 15 – May 6
🥦 Broccoli Mar 18 – Apr 1 Apr 15 – Apr 29
🥬 Kale Mar 25 – Apr 8 Apr 8 – Apr 22 Apr 8 – Apr 22
🥒 Cucumbers Apr 8 – Apr 15 May 13 – May 20 May 13 – May 20
🥒 Zucchini Apr 8 – Apr 15 May 13 – May 20 May 13 – May 20
🫘 Green Beans (Bush) May 13 – May 20
🌽 Sweet Corn May 13 – May 20
🌿 Basil Mar 25 – Apr 8 May 13 – May 20 May 20 – May 27
🧄 Garlic Fall: Aug 23 – Sep 20

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Missoula 6 NW Wfo's dates automatically after a lookup.

Reading the season in Missoula 6 NW Wfo

Roughly 151 frost-free days gives Missoula 6 NW Wfo gardeners room for nearly every common vegetable. Warm-season crops go out after May 6; a fall garden sown in late summer matures comfortably before the Oct 4 frost.

Frequently asked questions

When is the last frost in Missoula 6 NW Wfo, MT?

The average last spring frost in Missoula 6 NW Wfo is around May 6, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Missoula 6 NW Wfo, MT?

The average first fall frost in Missoula 6 NW Wfo arrives around Oct 4. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Missoula 6 NW Wfo?

About 151 frost-free days on average, from May 6 to Oct 4. That fits nearly all common vegetables, though the longest-season melons and sweet potatoes benefit from transplants.

What USDA zone is Missoula 6 NW Wfo in?

USDA zone 6b on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.