Carter County climate

Carter County Frost Dates and Growing Season

NOAA 1991-2020 normals for Ridgeway 1 S, 7.1 km from Carter County, elevation 3316 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ridgeway 1 S. 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 17 and the first fall freeze around September 22, a growing season of about 127 days.

Median at 36°F
last May 29, first September 12
Median at 32°F
last May 17, first September 22
Median at 28°F
last May 6, first October 1

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 17Jun 10Jun 4Jun 1May 29May 26May 24May 21May 16
32°FJun 1May 27May 24May 21May 17May 15May 12May 9May 5
28°FMay 21May 15May 11May 8May 6May 3May 1Apr 28Apr 23
24°FMay 10May 5May 2Apr 30Apr 27Apr 25Apr 21Apr 17Apr 12
20°FApr 30Apr 26Apr 21Apr 17Apr 15Apr 12Apr 9Apr 4Mar 30
16°FApr 21Apr 16Apr 12Apr 9Apr 4Apr 1Mar 29Mar 23Mar 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°FAug 24Sep 1Sep 5Sep 9Sep 12Sep 15Sep 18Sep 22Sep 26
32°FSep 5Sep 11Sep 15Sep 18Sep 22Sep 25Sep 29Oct 1Oct 5
28°FSep 15Sep 22Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 15
24°FSep 25Oct 1Oct 4Oct 7Oct 11Oct 15Oct 17Oct 21Oct 25
20°FOct 3Oct 9Oct 14Oct 17Oct 20Oct 23Oct 26Oct 29Nov 3
16°FOct 11Oct 17Oct 21Oct 25Oct 28Oct 31Nov 3Nov 6Nov 11

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°F12311611210710399948777
32°F146140135131127122118113105
28°F167160155151147144140135128
24°F188181176171166162157152145
20°F210203197192187183178173165
16°F229221215210206202197191184

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
8,011
Cooling degree days, base 65°F
503
Growing degree days, base 40°F
4,065
Growing degree days, base 45°F
3,073
Growing degree days, base 50°F
2,221
Growing degree days, base 55°F
1,511
Growing degree days, base 60°F
934

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42400
February1,19800
March98906
April648036
May3627169
June11864399
July24208649
August41179604
September21742299
October627257
November1,00703
December1,35600

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 7.1 km from Carter 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 USC00247034 (Ridgeway 1 S). Public domain.