McKee climate

McKee Frost Dates and Growing Season

NOAA 1991-2020 normals for Heidelberg, 24.4 km from McKee, elevation 665 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Heidelberg. 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 April 17 and the first fall freeze around October 22, a growing season of about 189 days.

Median at 36°F
last April 28, first October 14
Median at 32°F
last April 17, first October 22
Median at 28°F
last April 3, first November 2

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 16May 9May 5May 1Apr 28Apr 24Apr 21Apr 18Apr 13
32°FMay 5Apr 30Apr 24Apr 20Apr 17Apr 14Apr 10Apr 5Mar 31
28°FApr 22Apr 14Apr 10Apr 5Apr 3Mar 31Mar 29Mar 24Mar 18
24°FApr 6Apr 1Mar 30Mar 26Mar 22Mar 19Mar 15Mar 10Mar 2
20°FMar 29Mar 23Mar 18Mar 15Mar 11Mar 7Mar 3Feb 27Feb 18
16°FMar 19Mar 13Mar 7Mar 3Feb 27Feb 22Feb 16Feb 9Feb 2

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°FOct 4Oct 7Oct 10Oct 12Oct 14Oct 17Oct 19Oct 21Oct 25
32°FOct 10Oct 15Oct 17Oct 19Oct 22Oct 25Oct 29Nov 1Nov 5
28°FOct 19Oct 25Oct 29Nov 1Nov 2Nov 5Nov 8Nov 12Nov 17
24°FNov 1Nov 5Nov 9Nov 12Nov 15Nov 18Nov 23Nov 28Dec 3
20°FNov 10Nov 16Nov 21Nov 25Nov 28Dec 1Dec 5Dec 11Dec 20
16°FNov 21Nov 28Dec 2Dec 7Dec 13Dec 19Dec 24Dec 30Jan 8

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°F186180175172168164159154147
32°F209202197193189184180174166
28°F236229222217214209205199190
24°F263255248243238233229223216
20°F289280274268262257252246238
16°F320308302295289282276267258

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
4,509
Cooling degree days, base 65°F
1,123
Growing degree days, base 40°F
6,416
Growing degree days, base 45°F
5,058
Growing degree days, base 50°F
3,849
Growing degree days, base 55°F
2,792
Growing degree days, base 60°F
1,881

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January950011
February779012
March606476
April30523223
May11382437
June12224661
July0329793
August2294758
September42147555
October28018237
November574169
December847017

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 24.4 km from McKee. 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 USC00153741 (Heidelberg). Public domain.