Austin 1 W, MT Frost Dates & Growing Season

The two dates every Austin 1 W garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Jun 4
~50% chance of frost after
First fall frost
Sep 14
~50% chance of frost before
Growing season
102 days
frost-free stretch
USDA zone
≈ 4b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost May 18 Jun 4 Jun 18
First fall frost Sep 27 Sep 14 Aug 30
Hard freeze (28°F), median last May 14 · first Sep 26

Computed from NOAA 1991–2020 climate normals at the AUSTIN 1 W 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 Austin 1 W

Computed from Austin 1 W's own frost dates. Click any crop for the full zone-4 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Apr 9 – Apr 23 Jun 11 – Jun 18
🫑 Peppers Mar 26 – Apr 9 Jun 18 – Jun 25
🥬 Lettuce Apr 23 – May 7 May 7 – May 21 May 7 – Jun 4
🫛 Peas Apr 23 – May 7
🥕 Carrots May 14 – Jun 4
🥦 Broccoli Apr 16 – Apr 30 May 14 – May 28
🥬 Kale Apr 23 – May 7 May 7 – May 21 May 7 – May 21
🥒 Cucumbers May 7 – May 14 Jun 11 – Jun 18 Jun 11 – Jun 18
🥒 Zucchini May 7 – May 14 Jun 11 – Jun 18 Jun 11 – Jun 18
🫘 Green Beans (Bush) Jun 11 – Jun 18
🌽 Sweet Corn Jun 11 – Jun 18
🌿 Basil Apr 23 – May 7 Jun 11 – Jun 18 Jun 18 – Jun 25
🧄 Garlic Fall: Aug 3 – Aug 31

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 Austin 1 W's dates automatically after a lookup.

Reading the season in Austin 1 W

At about 102 frost-free days, Austin 1 W rewards efficiency: start warm-season crops indoors, favor short-season varieties, and lean on cold-tolerant crops — peas, kale, roots — that shrug off the shoulder-season frosts on either end.

Frequently asked questions

When is the last frost in Austin 1 W, MT?

The average last spring frost in Austin 1 W is around Jun 4, 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 Austin 1 W, MT?

The average first fall frost in Austin 1 W arrives around Sep 14. 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 Austin 1 W?

About 102 frost-free days on average, from Jun 4 to Sep 14. That favors short-season varieties and transplants for warm-season crops, with cool-season vegetables doing the heavy lifting in spring and fall.

What USDA zone is Austin 1 W in?

USDA zone 4b 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.