Rexburg climate

Rexburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Rexburg Madison CO AP, 1.5 km from Rexburg, elevation 4858 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rexburg Madison CO AP. 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 15 and the first fall freeze around September 23, a growing season of about 129 days.

Median at 36°F
last June 6, first September 10
Median at 32°F
last May 15, first September 23
Median at 28°F
last May 1, first October 5

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°FJun 23Jun 18Jun 14Jun 10Jun 6Jun 3May 30May 24May 19
32°FJun 3May 26May 21May 18May 15May 11May 9May 5May 1
28°FMay 13May 9May 6May 3May 1Apr 28Apr 25Apr 21Apr 17
24°FMay 2Apr 27Apr 23Apr 19Apr 15Apr 12Apr 9Apr 5Apr 1
20°FApr 18Apr 11Apr 6Apr 3Mar 31Mar 27Mar 22Mar 17Mar 11
16°FApr 2Mar 29Mar 23Mar 19Mar 15Mar 12Mar 9Mar 7Mar 3

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 30Sep 2Sep 5Sep 8Sep 10Sep 13Sep 17Sep 20Sep 25
32°FSep 8Sep 13Sep 18Sep 20Sep 23Sep 26Sep 28Oct 2Oct 7
28°FSep 20Sep 26Sep 30Oct 2Oct 5Oct 8Oct 12Oct 16Oct 20
24°FOct 2Oct 8Oct 13Oct 17Oct 19Oct 22Oct 25Oct 29Nov 3
20°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 2Nov 5Nov 9Nov 15
16°FOct 24Oct 29Nov 3Nov 6Nov 9Nov 13Nov 17Nov 21Nov 26

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°F1191101051009692888376
32°F150143138134129124119112103
28°F177169165160157153149143135
24°F206199194188184180175170163
20°F233226221216211207202196187
16°F257248243239234230226221212

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
7,893
Cooling degree days, base 65°F
258
Growing degree days, base 40°F
3,650
Growing degree days, base 45°F
2,671
Growing degree days, base 50°F
1,847
Growing degree days, base 55°F
1,170
Growing degree days, base 60°F
638

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,38400
February1,14500
March92902
April635020
May3803141
June16623314
July23122564
August3898526
September24111242
October628038
November98700
December1,33900

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 1.5 km from Rexburg. 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 USW00094194 (Rexburg Madison CO AP). Public domain.