Smith County climate

Smith County Frost Dates and Growing Season

NOAA 1991-2020 normals for Raleigh 6N, 14.6 km from Smith County, elevation 446 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Raleigh 6N. 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 March 28 and the first fall freeze around November 3, a growing season of about 221 days.

Median at 36°F
last April 10, first October 25
Median at 32°F
last March 28, first November 3
Median at 28°F
last March 12, first November 15

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°FApr 28Apr 23Apr 17Apr 13Apr 10Apr 7Apr 3Mar 30Mar 22
32°FApr 15Apr 9Apr 5Apr 1Mar 28Mar 24Mar 19Mar 13Mar 6
28°FApr 3Mar 27Mar 22Mar 17Mar 12Mar 7Mar 2Feb 26Feb 18
24°FMar 19Mar 11Mar 5Feb 28Feb 23Feb 19Feb 13Feb 4Jan 28
20°FMar 5Feb 27Feb 18Feb 9Feb 3Jan 30Jan 25Jan 16Jan 3
16°FFeb 22Feb 7Feb 1Jan 29Jan 24Jan 19Jan 13Jan 5Dec 29

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 12Oct 16Oct 19Oct 22Oct 25Oct 28Nov 1Nov 4Nov 9
32°FOct 20Oct 24Oct 28Nov 1Nov 3Nov 6Nov 10Nov 15Nov 22
28°FOct 30Nov 3Nov 7Nov 11Nov 15Nov 19Nov 24Dec 1Dec 7
24°FNov 8Nov 15Nov 21Nov 26Dec 1Dec 5Dec 11Dec 22Jan 3
20°FNov 23Dec 2Dec 8Dec 15Dec 24Dec 31Jan 4Jan 11Jan 24
16°FDec 7Dec 20Dec 29Jan 1Jan 6Jan 12Jan 18Jan 26Feb 3

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°F221212207202198194189184177
32°F248239232227221215210204197
28°F279267259253248243235228221
24°F319306297288281274266258249
20°F363344334326319310303294282
16°F365365365365353343335327312

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
93% of years
16°F or colder
64% 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
2,733
Cooling degree days, base 65°F
1,808
Growing degree days, base 40°F
8,359
Growing degree days, base 45°F
6,750
Growing degree days, base 50°F
5,281
Growing degree days, base 55°F
3,959
Growing degree days, base 60°F
2,796

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January644366
February479489
March32914209
April14953365
May33182614
June0345795
July0436901
August0414879
September9267708
October13876412
November37410158
December579587

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 14.6 km from Smith 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 USC00227276 (Raleigh 6N). Public domain.