Belgrade climate

Belgrade Frost Dates and Growing Season

NOAA 1991-2020 normals for Bozeman Gallatin Fld, 1.8 km from Belgrade, elevation 4427 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bozeman Gallatin Fld. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 26 and the first fall freeze around September 16, a growing season of about 112 days.

Median at 36°F
last June 16, first September 4
Median at 32°F
last May 26, first September 16
Median at 28°F
last May 9, first September 28

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FJul 2Jun 25Jun 22Jun 18Jun 16Jun 12Jun 9Jun 4May 30
32°FJun 12Jun 5Jun 2May 29May 26May 23May 20May 16May 11
28°FMay 24May 19May 15May 11May 9May 6May 4May 1Apr 27
24°FMay 10May 6May 3May 1Apr 28Apr 26Apr 22Apr 18Apr 13
20°FMay 2Apr 27Apr 23Apr 19Apr 15Apr 12Apr 8Apr 5Apr 1
16°FApr 18Apr 12Apr 7Apr 4Apr 2Mar 30Mar 25Mar 19Mar 12

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FAug 20Aug 26Aug 30Sep 1Sep 4Sep 6Sep 9Sep 12Sep 17
32°FSep 2Sep 6Sep 10Sep 12Sep 16Sep 19Sep 21Sep 24Sep 29
28°FSep 15Sep 19Sep 23Sep 26Sep 28Oct 1Oct 3Oct 6Oct 10
24°FSep 25Sep 30Oct 3Oct 6Oct 8Oct 12Oct 15Oct 18Oct 23
20°FOct 3Oct 7Oct 12Oct 16Oct 19Oct 22Oct 26Oct 29Nov 2
16°FOct 10Oct 18Oct 22Oct 25Oct 29Nov 1Nov 3Nov 6Nov 11

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F989187837975706356
32°F1321251201161121081029688
28°F159153148144140137133128120
24°F182176172168164159155150144
20°F206200194190185180175170163
16°F233225219214210205201194185

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
8,245
Cooling degree days, base 65°F
232
Growing degree days, base 40°F
3,453
Growing degree days, base 45°F
2,493
Growing degree days, base 50°F
1,695
Growing degree days, base 55°F
1,055
Growing degree days, base 60°F
566

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,35800
February1,14400
March96102
April684017
May4261114
June19817277
July42117540
August6487490
September27411216
October670038
November1,05202
December1,37300

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 1.8 km from Belgrade. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00024132 (Bozeman Gallatin Fld). Public domain.