Sanborn climate

Sanborn Frost Dates and Growing Season

NOAA 1991-2020 normals for Sanborn, 0.5 km from Sanborn, elevation 1551 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sanborn. 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 1 and the first fall freeze around October 7, a growing season of about 160 days.

Median at 36°F
last May 8, first September 28
Median at 32°F
last May 1, first October 7
Median at 28°F
last April 20, first October 17

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

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 15Sep 20Sep 23Sep 26Sep 28Oct 1Oct 4Oct 7Oct 11
32°FSep 23Sep 28Oct 1Oct 4Oct 7Oct 10Oct 12Oct 16Oct 20
28°FOct 1Oct 7Oct 11Oct 14Oct 17Oct 20Oct 23Oct 26Oct 31
24°FOct 13Oct 17Oct 21Oct 23Oct 26Oct 29Nov 1Nov 4Nov 8
20°FOct 22Oct 26Oct 30Nov 1Nov 3Nov 6Nov 8Nov 13Nov 18
16°FOct 29Nov 1Nov 4Nov 7Nov 11Nov 14Nov 17Nov 21Nov 27

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°F160154150146142139135130123
32°F179172167163160156152147141
28°F199192187183179174170165158
24°F218211206201197193188183176
20°F236228222217213209205200192
16°F251244239235230225219214207

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
7,802
Cooling degree days, base 65°F
663
Growing degree days, base 40°F
4,629
Growing degree days, base 45°F
3,608
Growing degree days, base 50°F
2,694
Growing degree days, base 55°F
1,893
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
January1,54800
February1,28100
March1,029010
April598366
May26239274
June46150554
July9234690
August20169614
September15864368
October5216108
November953011
December1,37600

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 0.5 km from Sanborn. 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 USC00137386 (Sanborn). Public domain.