Caldwell County climate

Caldwell County Frost Dates and Growing Season

NOAA 1991-2020 normals for Hamilton 2W, 10.6 km from Caldwell County, elevation 900 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hamilton 2W. 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 23 and the first fall freeze around October 17, a growing season of about 175 days.

Median at 36°F
last May 2, first October 7
Median at 32°F
last April 23, first October 17
Median at 28°F
last April 13, first October 26

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

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 23Sep 29Oct 1Oct 4Oct 7Oct 10Oct 12Oct 15Oct 20
32°FOct 2Oct 7Oct 12Oct 15Oct 17Oct 20Oct 22Oct 25Oct 29
28°FOct 13Oct 18Oct 21Oct 23Oct 26Oct 29Oct 31Nov 2Nov 8
24°FOct 21Oct 26Oct 29Nov 1Nov 3Nov 5Nov 9Nov 12Nov 18
20°FNov 1Nov 4Nov 7Nov 10Nov 13Nov 15Nov 19Nov 24Dec 1
16°FNov 7Nov 12Nov 16Nov 20Nov 24Nov 28Dec 1Dec 4Dec 9

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°F174168164159156152148143136
32°F195189183179175171167162157
28°F215208204199196192187182175
24°F238230225220215211206202196
20°F260251245241236232227221213
16°F279272266261256252247240232

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
5,790
Cooling degree days, base 65°F
1,101
Growing degree days, base 40°F
5,824
Growing degree days, base 45°F
4,622
Growing degree days, base 50°F
3,550
Growing degree days, base 55°F
2,604
Growing degree days, base 60°F
1,785

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22701
February98306
March741247
April40810150
May15271394
June15225660
July2356818
August5302762
September86117484
October36218191
November724134
December1,08603

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 10.6 km from Caldwell County. 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 USC00233568 (Hamilton 2W). Public domain.