Dickinson climate

Dickinson Frost Dates and Growing Season

NOAA 1991-2020 normals for Dickinson, 1.6 km from Dickinson, elevation 2460 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dickinson. 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 20 and the first fall freeze around September 22, a growing season of about 123 days.

Median at 36°F
last May 31, first September 12
Median at 32°F
last May 20, first September 22
Median at 28°F
last May 10, first September 29

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 17Jun 10Jun 5Jun 2May 31May 28May 26May 24May 19
32°FJun 1May 28May 25May 23May 20May 17May 15May 12May 8
28°FMay 24May 19May 15May 12May 10May 7May 4May 2Apr 27
24°FMay 14May 9May 5May 2Apr 30Apr 28Apr 24Apr 20Apr 15
20°FMay 3Apr 29Apr 26Apr 23Apr 20Apr 16Apr 14Apr 10Apr 6
16°FApr 24Apr 20Apr 16Apr 13Apr 10Apr 8Apr 5Apr 1Mar 26

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 27Sep 2Sep 6Sep 9Sep 12Sep 15Sep 17Sep 20Sep 24
32°FSep 8Sep 13Sep 16Sep 19Sep 22Sep 24Sep 26Sep 29Oct 3
28°FSep 16Sep 20Sep 24Sep 26Sep 29Oct 1Oct 4Oct 7Oct 13
24°FSep 23Sep 28Oct 1Oct 4Oct 6Oct 9Oct 13Oct 16Oct 20
20°FOct 1Oct 5Oct 9Oct 13Oct 15Oct 18Oct 21Oct 25Oct 30
16°FOct 8Oct 14Oct 18Oct 22Oct 25Oct 27Oct 31Nov 3Nov 9

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°F12011511010510299958981
32°F140134130126123119115111104
28°F159154149146141138134129123
24°F178172168164159156152146140
20°F199191185182178174170165157
16°F219212207202198193189183176

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
8,755
Cooling degree days, base 65°F
406
Growing degree days, base 40°F
3,765
Growing degree days, base 45°F
2,833
Growing degree days, base 50°F
2,024
Growing degree days, base 55°F
1,342
Growing degree days, base 60°F
802

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,56100
February1,30100
March1,11302
April714030
May3897158
June13355377
July39164590
August56146556
September25833261
October687147
November1,06203
December1,44300

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 1.6 km from Dickinson. 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 USC00322188 (Dickinson). Public domain.