Hollins climate

Hollins Frost Dates and Growing Season

NOAA 1991-2020 normals for Roanoke 8 N, 2.7 km from Hollins, elevation 1157 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Roanoke 8 N. 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 11 and the first fall freeze around October 28, a growing season of about 198 days.

Median at 36°F
last April 27, first October 20
Median at 32°F
last April 11, first October 28
Median at 28°F
last March 30, first November 6

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 13May 8May 4May 1Apr 27Apr 23Apr 19Apr 16Apr 11
32°FMay 2Apr 23Apr 18Apr 15Apr 11Apr 8Apr 5Apr 2Mar 28
28°FApr 11Apr 6Apr 3Apr 1Mar 30Mar 26Mar 23Mar 19Mar 14
24°FApr 2Mar 28Mar 24Mar 20Mar 17Mar 13Mar 9Mar 5Feb 28
20°FMar 22Mar 17Mar 12Mar 8Mar 4Feb 28Feb 24Feb 18Feb 10
16°FMar 12Mar 6Feb 28Feb 24Feb 18Feb 12Feb 7Feb 2Jan 25

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 5Oct 10Oct 13Oct 17Oct 20Oct 23Oct 25Oct 28Nov 1
32°FOct 14Oct 20Oct 23Oct 26Oct 28Oct 31Nov 1Nov 4Nov 9
28°FOct 25Oct 30Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 21
24°FNov 2Nov 7Nov 11Nov 14Nov 18Nov 23Nov 28Dec 3Dec 10
20°FNov 15Nov 22Nov 27Dec 1Dec 4Dec 9Dec 14Dec 21Dec 30
16°FDec 2Dec 9Dec 16Dec 22Dec 27Jan 1Jan 5Jan 12Jan 21

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°F195189184180177173168163157
32°F217211207202198195191185178
28°F244236231226222218214209203
24°F274264258252246242237232226
20°F303295288282277272266259248
16°F334325318312306300295288278

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
4,432
Cooling degree days, base 65°F
1,014
Growing degree days, base 40°F
6,251
Growing degree days, base 45°F
4,884
Growing degree days, base 50°F
3,680
Growing degree days, base 55°F
2,635
Growing degree days, base 60°F
1,743

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91407
February757011
March606265
April30913198
May11769420
June13196633
July1313776
August3278741
September48126528
October27517235
November571154
December818013

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 2.7 km from Hollins. 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 USC00447278 (Roanoke 8 N). Public domain.