Bennett County climate

Bennett County Frost Dates and Growing Season

NOAA 1991-2020 normals for Martin, 6.3 km from Bennett County, elevation 3330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Martin. 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 13 and the first fall freeze around October 2, a growing season of about 141 days.

Median at 36°F
last May 22, first September 23
Median at 32°F
last May 13, first October 2
Median at 28°F
last May 2, first October 12

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 7Jun 1May 28May 25May 22May 20May 17May 14May 10
32°FMay 27May 22May 19May 15May 13May 10May 7May 4Apr 30
28°FMay 17May 10May 6May 3May 2Apr 30Apr 27Apr 23Apr 18
24°FMay 6May 1Apr 29Apr 25Apr 22Apr 19Apr 15Apr 11Apr 4
20°FApr 28Apr 22Apr 18Apr 14Apr 10Apr 7Apr 4Mar 31Mar 25
16°FApr 20Apr 13Apr 9Apr 5Apr 3Mar 30Mar 26Mar 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°FSep 8Sep 15Sep 18Sep 21Sep 23Sep 26Sep 29Oct 1Oct 5
32°FSep 18Sep 23Sep 27Sep 30Oct 2Oct 5Oct 7Oct 11Oct 15
28°FSep 30Oct 4Oct 7Oct 10Oct 12Oct 15Oct 17Oct 20Oct 24
24°FOct 8Oct 13Oct 16Oct 19Oct 21Oct 23Oct 26Oct 29Nov 2
20°FOct 14Oct 18Oct 22Oct 25Oct 28Oct 30Nov 1Nov 5Nov 10
16°FOct 20Oct 25Oct 28Oct 31Nov 3Nov 5Nov 10Nov 14Nov 19

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°F140134130126122118114109102
32°F158153148144141137133129120
28°F180173169165162157154148141
24°F204196191186181177172168161
20°F224215210205200196191185178
16°F240232226221216211207201191

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
7,059
Cooling degree days, base 65°F
697
Growing degree days, base 40°F
4,665
Growing degree days, base 45°F
3,593
Growing degree days, base 50°F
2,664
Growing degree days, base 55°F
1,873
Growing degree days, base 60°F
1,214

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27700
February1,07401
March875019
April592160
May30718218
June75105482
July11267720
August20223668
September15180393
October539492
November909011
December1,23000

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 6.3 km from Bennett County. 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 USC00395281 (Martin). Public domain.