When is the last frost in Granby, CO?

For ZIP code 80446, the average last spring frost (32°F) is June 13, based on NOAA 1991-2020 climate normals for the Grand Lake 6 Ssw, CO weather station. There is a 1-in-10 chance of a frost after June 28.

When is the first frost in Granby, CO?

The average first fall frost (32°F) is September 7. There is a 1-in-10 chance of frost by August 21, so tender plants are at risk from that point on.

How long is the growing season in 80446?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 84 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 80446Granby, CO

The average last spring frost in Granby is June 13 and the average first fall frost is September 7, giving a typical growing season of about 84 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jun 13
Average first fall frost: Sep 7
Growing season: 84 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)	Jun 1 · Jun 13 · Jun 28	Aug 21 · Sep 7 · Sep 21	84 days	100%
Hard freeze (28°F)	May 12 · May 26 · Jun 10	Sep 8 · Sep 22 · Oct 4	118 days	100%

Where these dates come from

ZIP code 80446 is matched to the NOAA station Grand Lake 6 Ssw, CO, 13.4 km away, at 8,288 ft elevation (329 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Grand Lake 6 Ssw, CO (used)	8,288 ft	Jun 13	Sep 7
Fraser, CO	8,560 ft	—	—
Grand Lake 1 Nw, CO	8,721 ft	—	—
Williams Fork Dam, CO	7,618 ft	Jun 12	Sep 10

Frost dates near Granby

Tabernash, CO 80478 · last —, first —
Hot Sulphur Springs, CO 80451 · last Jun 12, first Sep 10
Fraser, CO 80442 · last —, first —
Grand Lake, CO 80447 · last —, first —
Parshall, CO 80468 · last —, first —
Winter Park, CO 80482 · last Jun 21, first Sep 2
Ward, CO 80481 · last Jun 5, first Sep 16
Allenspark, CO 80510 · last Jun 14, first Sep 12

Frequently asked questions

When is the last frost in Granby, CO?: For ZIP code 80446, the average last spring frost (32°F) is June 13, based on NOAA 1991-2020 climate normals for the Grand Lake 6 Ssw, CO weather station. There is a 1-in-10 chance of a frost after June 28.
When is the first frost in Granby, CO?: The average first fall frost (32°F) is September 7. There is a 1-in-10 chance of frost by August 21, so tender plants are at risk from that point on.
How long is the growing season in 80446?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 84 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.