Raven climate

Raven Frost Dates and Growing Season

NOAA 1991-2020 normals for Richlands, 5.5 km from Raven, elevation 1910 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Richlands. 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 27 and the first fall freeze around October 18, a growing season of about 173 days.

Median at 36°F
last May 7, first October 9
Median at 32°F
last April 27, first October 18
Median at 28°F
last April 13, first October 27

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 23May 18May 14May 10May 7May 4May 1Apr 28Apr 23
32°FMay 14May 7May 3Apr 30Apr 27Apr 23Apr 20Apr 17Apr 11
28°FMay 2Apr 24Apr 20Apr 16Apr 13Apr 9Apr 6Apr 2Mar 28
24°FApr 14Apr 9Apr 5Apr 2Mar 31Mar 27Mar 23Mar 19Mar 12
20°FApr 2Mar 29Mar 25Mar 21Mar 18Mar 14Mar 10Mar 5Feb 27
16°FMar 23Mar 19Mar 14Mar 9Mar 4Mar 1Feb 24Feb 17Feb 8

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 27Oct 1Oct 4Oct 7Oct 9Oct 12Oct 15Oct 18Oct 22
32°FOct 5Oct 9Oct 12Oct 15Oct 18Oct 20Oct 23Oct 26Nov 1
28°FOct 13Oct 18Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 9
24°FOct 23Oct 28Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 22
20°FNov 2Nov 7Nov 10Nov 14Nov 17Nov 21Nov 25Nov 29Dec 4
16°FNov 12Nov 18Nov 25Nov 28Dec 1Dec 5Dec 10Dec 17Dec 25

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°F172166161157154150145141135
32°F193186182177173170165159153
28°F217209204200195191186181173
24°F243235228224219215211206199
20°F274265257251246240235229222
16°F303293285280275269262255246

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
4,929
Cooling degree days, base 65°F
720
Growing degree days, base 40°F
5,675
Growing degree days, base 45°F
4,357
Growing degree days, base 50°F
3,209
Growing degree days, base 55°F
2,223
Growing degree days, base 60°F
1,391

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98007
February79909
March674044
April3804150
May15643361
June24141567
July3231693
August4204665
September6790474
October3408185
November629042
December873012

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 5.5 km from Raven. 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 USC00447174 (Richlands). Public domain.