Chatmoss climate

Chatmoss Frost Dates and Growing Season

NOAA 1991-2020 normals for Martinsville Fltr Plt, 7.1 km from Chatmoss, elevation 780 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Martinsville Fltr Plt. 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 24 and the first fall freeze around October 21, a growing season of about 179 days.

Median at 36°F
last May 5, first October 12
Median at 32°F
last April 24, first October 21
Median at 28°F
last April 13, first October 30

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

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 30Oct 4Oct 7Oct 10Oct 12Oct 14Oct 17Oct 20Oct 26
32°FOct 9Oct 13Oct 16Oct 19Oct 21Oct 25Oct 27Oct 31Nov 3
28°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 6Nov 11
24°FOct 27Oct 31Nov 2Nov 5Nov 8Nov 11Nov 13Nov 18Nov 26
20°FNov 5Nov 10Nov 13Nov 17Nov 20Nov 25Nov 29Dec 2Dec 8
16°FNov 16Nov 24Nov 28Dec 1Dec 5Dec 9Dec 15Dec 23Jan 1

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°F179172167163159155150145139
32°F197191187183179175170164157
28°F220214208203199195191185177
24°F248238232228223219214209203
20°F277268260254249244238232225
16°F312301293285280274268261252

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
4,342
Cooling degree days, base 65°F
1,085
Growing degree days, base 40°F
6,373
Growing degree days, base 45°F
4,994
Growing degree days, base 50°F
3,780
Growing degree days, base 55°F
2,728
Growing degree days, base 60°F
1,830

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January89609
February732013
March591165
April29614207
May10776436
June12221659
July0341806
August2289752
September46126530
October27317235
November571155
December815015

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 Chatmoss. 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 USC00445300 (Martinsville Fltr Plt). Public domain.