Shepherd climate

Shepherd Frost Dates and Growing Season

NOAA 1991-2020 normals for Huntley Exp Stn, 7.8 km from Shepherd, elevation 3034 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Huntley Exp Stn. 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 12 and the first fall freeze around September 25, a growing season of about 136 days.

Median at 36°F
last May 25, first September 14
Median at 32°F
last May 12, first September 25
Median at 28°F
last April 30, first October 4

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

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 1Sep 6Sep 9Sep 12Sep 14Sep 18Sep 20Sep 24Sep 29
32°FSep 13Sep 18Sep 20Sep 23Sep 25Sep 28Oct 1Oct 4Oct 8
28°FSep 23Sep 26Sep 29Oct 2Oct 4Oct 7Oct 11Oct 14Oct 18
24°FOct 1Oct 4Oct 9Oct 12Oct 15Oct 18Oct 20Oct 25Oct 29
20°FOct 8Oct 14Oct 18Oct 23Oct 26Oct 29Nov 1Nov 4Nov 9
16°FOct 16Oct 22Oct 28Oct 31Nov 3Nov 6Nov 9Nov 14Nov 20

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°F1281231191151111081039891
32°F153146142139136132128123117
28°F176168164160157153150145138
24°F200193187182178175170166158
20°F221215209205200195190185176
16°F243234228222218213207201193

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
7,355
Cooling degree days, base 65°F
483
Growing degree days, base 40°F
4,205
Growing degree days, base 45°F
3,154
Growing degree days, base 50°F
2,263
Growing degree days, base 55°F
1,523
Growing degree days, base 60°F
932

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29100
February1,07101
March90108
April595149
May3369188
June11059402
July21207651
August36170599
September20936299
October600263
November93504
December1,25100

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 7.8 km from Shepherd. 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 USC00244345 (Huntley Exp Stn). Public domain.