Benson climate

Benson Frost Dates and Growing Season

NOAA 1991-2020 normals for Benson, 1.2 km from Benson, elevation 1030 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Benson. 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 4 and the first fall freeze around October 3, a growing season of about 151 days.

Median at 36°F
last May 13, first September 26
Median at 32°F
last May 4, first October 3
Median at 28°F
last April 26, 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°FMay 26May 21May 18May 15May 13May 10May 8May 5Apr 30
32°FMay 17May 13May 10May 7May 4May 2Apr 30Apr 27Apr 22
28°FMay 8May 4May 1Apr 28Apr 26Apr 23Apr 19Apr 16Apr 11
24°FApr 30Apr 24Apr 21Apr 18Apr 15Apr 13Apr 10Apr 6Apr 3
20°FApr 22Apr 17Apr 13Apr 9Apr 6Apr 4Apr 2Mar 30Mar 23
16°FApr 15Apr 10Apr 6Apr 3Apr 1Mar 30Mar 25Mar 21Mar 15

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 14Sep 18Sep 21Sep 23Sep 26Sep 28Sep 30Oct 2Oct 6
32°FSep 21Sep 25Sep 28Sep 30Oct 3Oct 5Oct 8Oct 11Oct 15
28°FSep 28Oct 2Oct 5Oct 9Oct 12Oct 15Oct 18Oct 21Oct 26
24°FOct 7Oct 14Oct 17Oct 20Oct 23Oct 25Oct 28Nov 1Nov 4
20°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 14
16°FOct 27Nov 1Nov 3Nov 6Nov 8Nov 11Nov 14Nov 17Nov 22

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°F151146141137134130127122117
32°F170162158154151147143139132
28°F188182178174171166161157150
24°F208202197193189186182176170
20°F224218213209206203200194187
16°F241235229225221217213208202

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
8,378
Cooling degree days, base 65°F
643
Growing degree days, base 40°F
4,490
Growing degree days, base 45°F
3,504
Growing degree days, base 50°F
2,620
Growing degree days, base 55°F
1,842
Growing degree days, base 60°F
1,178

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,67400
February1,38900
March1,12405
April629254
May26436271
June47141545
July10232686
August23168611
September16260358
October567584
November1,01606
December1,47600

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 1.2 km from Benson. 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 USC00210667 (Benson). Public domain.