Red Lodge climate

Red Lodge Frost Dates and Growing Season

NOAA 1991-2020 normals for Red Lodge, 1.3 km from Red Lodge, elevation 5646 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Red Lodge. 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 June 3 and the first fall freeze around September 19, a growing season of about 106 days.

Median at 36°F
last June 19, first September 5
Median at 32°F
last June 3, first September 19
Median at 28°F
last May 17, first October 1

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 7Jun 30Jun 24Jun 21Jun 19Jun 16Jun 12Jun 9Jun 3
32°FJun 18Jun 13Jun 9Jun 5Jun 3May 31May 28May 24May 19
28°FJun 4May 30May 25May 22May 17May 14May 10May 5May 1
24°FMay 22May 14May 9May 6May 3Apr 30Apr 27Apr 23Apr 18
20°FMay 5Apr 30Apr 27Apr 23Apr 20Apr 17Apr 13Apr 9Apr 4
16°FApr 24Apr 19Apr 15Apr 12Apr 8Apr 4Apr 1Mar 28Mar 21

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 14Aug 23Aug 28Sep 2Sep 5Sep 8Sep 12Sep 16Sep 22
32°FAug 31Sep 6Sep 12Sep 15Sep 19Sep 23Sep 26Sep 30Oct 3
28°FSep 15Sep 21Sep 25Sep 28Oct 1Oct 3Oct 5Oct 9Oct 14
24°FSep 27Oct 1Oct 4Oct 6Oct 10Oct 13Oct 16Oct 20Oct 26
20°FOct 4Oct 8Oct 13Oct 16Oct 19Oct 22Oct 26Oct 31Nov 5
16°FOct 10Oct 16Oct 20Oct 24Oct 28Nov 1Nov 4Nov 9Nov 14

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°F1009185817772676050
32°F127121116110106101968981
28°F156149142138133127122116107
24°F182174170164159155150145135
20°F205198191187182177172167158
16°F226218213208202197192185178

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
8,055
Cooling degree days, base 65°F
197
Growing degree days, base 40°F
3,340
Growing degree days, base 45°F
2,381
Growing degree days, base 50°F
1,598
Growing degree days, base 55°F
970
Growing degree days, base 60°F
502

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21800
February1,10601
March97003
April723022
May488295
June23716247
July7087483
August8473458
September27618232
October655153
November98605
December1,24100

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 1.3 km from Red Lodge. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00246918 (Red Lodge). Public domain.