Coalfield climate

Coalfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Oak Ridge Atdd, 15.8 km from Coalfield, elevation 905 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oak Ridge Atdd. 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 5 and the first fall freeze around November 1, a growing season of about 210 days.

Median at 36°F
last April 17, first October 23
Median at 32°F
last April 5, first November 1
Median at 28°F
last March 23, first November 11

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

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 10Oct 14Oct 18Oct 21Oct 23Oct 26Oct 28Oct 31Nov 4
32°FOct 19Oct 24Oct 27Oct 30Nov 1Nov 3Nov 5Nov 8Nov 13
28°FOct 31Nov 3Nov 6Nov 8Nov 11Nov 14Nov 17Nov 22Nov 28
24°FNov 8Nov 13Nov 16Nov 20Nov 25Nov 29Dec 2Dec 8Dec 18
20°FNov 19Nov 26Dec 1Dec 5Dec 10Dec 17Dec 23Dec 29Jan 6
16°FDec 2Dec 10Dec 18Dec 24Dec 30Jan 2Jan 8Jan 13Jan 23

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°F208202197193189186181176169
32°F231224218214210206201197191
28°F260251245239235230225219213
24°F292282273267262257251245236
20°F327314306300293286279272261
16°F358344335331324317309301291

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
95% 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
3,732
Cooling degree days, base 65°F
1,414
Growing degree days, base 40°F
7,184
Growing degree days, base 45°F
5,715
Growing degree days, base 50°F
4,405
Growing degree days, base 55°F
3,259
Growing degree days, base 60°F
2,261

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January840016
February651025
March4784111
April21927280
May62121525
June4275721
July0389854
August0366831
September21195624
October19935317
November509279
December749023

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 15.8 km from Coalfield. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00003841 (Oak Ridge Atdd). Public domain.