Smithland climate

Smithland Frost Dates and Growing Season

NOAA 1991-2020 normals for Smithland L&d, 3.8 km from Smithland, elevation 357 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Smithland L&d. 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 3 and the first fall freeze around October 30, a growing season of about 207 days.

Median at 36°F
last April 16, first October 21
Median at 32°F
last April 3, first October 30
Median at 28°F
last March 23, first November 8

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

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 9Oct 13Oct 17Oct 19Oct 21Oct 24Oct 26Oct 29Nov 1
32°FOct 17Oct 22Oct 25Oct 28Oct 30Nov 1Nov 4Nov 7Nov 12
28°FOct 27Nov 1Nov 3Nov 5Nov 8Nov 11Nov 14Nov 19Nov 25
24°FNov 4Nov 9Nov 12Nov 15Nov 19Nov 23Nov 28Dec 1Dec 7
20°FNov 11Nov 17Nov 23Nov 28Dec 1Dec 5Dec 9Dec 15Dec 25
16°FNov 22Nov 30Dec 4Dec 9Dec 15Dec 23Dec 27Jan 1Jan 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°F206200196192188184180175168
32°F228221216211207203199194188
28°F255246240235230225221214207
24°F279269263257253248242236228
20°F304294287281276270263257248
16°F331320312306301295288281271

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
99% 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
4,297
Cooling degree days, base 65°F
1,465
Growing degree days, base 40°F
6,948
Growing degree days, base 45°F
5,567
Growing degree days, base 50°F
4,329
Growing degree days, base 55°F
3,230
Growing degree days, base 60°F
2,277

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January953012
February766017
March573485
April26527251
May77118506
June5294739
July0411876
August1377842
September30193614
October23538293
November550377
December842018

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 3.8 km from Smithland. 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 USC00118020 (Smithland L&d). Public domain.