When is the last frost in Dupuyer, MT?

For ZIP code 59432, the average last spring frost (32°F) is June 9, based on NOAA 1991-2020 climate normals for the Blackleaf, MT weather station. There is a 1-in-10 chance of a frost after July 2.

When is the first frost in Dupuyer, MT?

The average first fall frost (32°F) is September 3. There is a 1-in-10 chance of frost by August 19, so tender plants are at risk from that point on.

How long is the growing season in 59432?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 86 days long.

Are these frost dates a forecast?

No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.

Frost dates for 59432Dupuyer, MT

The average last spring frost in Dupuyer is June 9 and the average first fall frost is September 3, giving a typical growing season of about 86 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jun 9
Average first fall frost: Sep 3
Growing season: 86 days

Frost risk by date

NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.

Spring dates: chance of a frost AFTER the date. Fall dates: chance of a frost BEFORE the date.
Temperature	Last spring: 90% / 50% / 10% chance	First fall: 10% / 50% / 90% chance	Growing season (50%)	Years with at least one
Light frost (36°F)	—	—	53 days	100%
Frost / freeze (32°F)	May 25 · Jun 9 · Jul 2	Aug 19 · Sep 3 · Sep 18	86 days	100%
Hard freeze (28°F)	May 10 · May 23 · Jun 6	Sep 2 · Sep 17 · Oct 1	116 days	100%

Where these dates come from

ZIP code 59432 is matched to the NOAA station Blackleaf, MT, 20.5 km away, at 4,235 ft elevation (114 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Blackleaf, MT (used)	4,235 ft	Jun 9	Sep 3
Valier, MT	3,807 ft	May 17	Sep 24
Bynum 4 Sse, MT	4,039 ft	May 16	Sep 27
Conrad, MT	3,550 ft	May 20	Sep 19

Frost dates near Dupuyer

Pendroy, MT 59467 · last Jun 9, first Sep 3
Valier, MT 59486 · last May 17, first Sep 24
Heart Butte, MT 59448 · last Jun 8, first Sep 5
Bynum, MT 59419 · last May 28, first Sep 12
Conrad, MT 59425 · last May 20, first Sep 19
Choteau, MT 59422 · last May 28, first Sep 12
Ethridge, MT 59435 · last May 23, first Sep 16
Cut Bank, MT 59427 · last May 24, first Sep 15

Frequently asked questions

When is the last frost in Dupuyer, MT?: For ZIP code 59432, the average last spring frost (32°F) is June 9, based on NOAA 1991-2020 climate normals for the Blackleaf, MT weather station. There is a 1-in-10 chance of a frost after July 2.
When is the first frost in Dupuyer, MT?: The average first fall frost (32°F) is September 3. There is a 1-in-10 chance of frost by August 19, so tender plants are at risk from that point on.
How long is the growing season in 59432?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 86 days long.
Are these frost dates a forecast?: No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.