When is the last frost in Richland, MT?

For ZIP code 59260, the average last spring frost (32°F) is June 5, based on NOAA 1991-2020 climate normals for the Opheim 12 Sse, MT weather station. There is a 1-in-10 chance of a frost after June 23.

When is the first frost in Richland, MT?

The average first fall frost (32°F) is September 2. There is a 1-in-10 chance of frost by August 15, so tender plants are at risk from that point on.

How long is the growing season in 59260?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 89 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 59260Richland, MT

The average last spring frost in Richland is June 5 and the average first fall frost is September 2, giving a typical growing season of about 89 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jun 5
Average first fall frost: Sep 2
Growing season: 89 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)	—	—	55 days	100%
Frost / freeze (32°F)	May 22 · Jun 5 · Jun 23	Aug 15 · Sep 2 · Sep 17	89 days	100%
Hard freeze (28°F)	May 12 · May 24 · Jun 6	Aug 31 · Sep 14 · Sep 25	112 days	100%

Where these dates come from

ZIP code 59260 is matched to the NOAA station Opheim 12 Sse, MT, 15.2 km away, at 2,936 ft elevation (42 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Opheim 12 Sse, MT (used)	2,936 ft	Jun 5	Sep 2
St Marie, MT	2,756 ft	May 13	Sep 27
Opheim 10 N, MT	2,878 ft	Jun 1	Sep 7
Scobey 4 Nw, MT	2,390 ft	May 28	Sep 6

Frost dates near Richland

Larslan, MT 59244 · last Jun 5, first Sep 2
Glentana, MT 59240 · last Jun 5, first Sep 2
Peerless, MT 59253 · last Jun 5, first Sep 2
Opheim, MT 59250 · last Jun 1, first Sep 7
Frazer, MT 59225 · last May 13, first Sep 27
Saint Marie, MT 59231 · last May 13, first Sep 27
Scobey, MT 59263 · last May 28, first Sep 6
Nashua, MT 59248 · last May 12, first Sep 24

Frequently asked questions

When is the last frost in Richland, MT?: For ZIP code 59260, the average last spring frost (32°F) is June 5, based on NOAA 1991-2020 climate normals for the Opheim 12 Sse, MT weather station. There is a 1-in-10 chance of a frost after June 23.
When is the first frost in Richland, MT?: The average first fall frost (32°F) is September 2. There is a 1-in-10 chance of frost by August 15, so tender plants are at risk from that point on.
How long is the growing season in 59260?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 89 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.