Roanoke climate

Roanoke Frost Dates and Growing Season

NOAA 1991-2020 normals for Minonk, 18.9 km from Roanoke, elevation 750 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Minonk. 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 26 and the first fall freeze around October 17, a growing season of about 173 days.

Median at 36°F
last May 5, first October 6
Median at 32°F
last April 26, first October 17
Median at 28°F
last April 15, first October 28

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 7May 5May 2Apr 29Apr 26Apr 21
32°FMay 10May 5May 1Apr 29Apr 26Apr 23Apr 20Apr 16Apr 11
28°FMay 1Apr 26Apr 22Apr 18Apr 15Apr 12Apr 8Apr 5Apr 1
24°FApr 21Apr 15Apr 9Apr 6Apr 4Apr 1Mar 29Mar 24Mar 18
20°FApr 9Apr 3Mar 31Mar 28Mar 24Mar 20Mar 17Mar 13Mar 8
16°FMar 31Mar 25Mar 20Mar 16Mar 13Mar 10Mar 7Mar 3Feb 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°FSep 23Sep 27Oct 1Oct 4Oct 6Oct 9Oct 12Oct 15Oct 20
32°FOct 1Oct 7Oct 12Oct 14Oct 17Oct 20Oct 22Oct 25Oct 29
28°FOct 14Oct 19Oct 22Oct 25Oct 28Oct 30Nov 1Nov 3Nov 9
24°FOct 25Oct 30Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 21
20°FNov 2Nov 7Nov 10Nov 13Nov 17Nov 19Nov 23Nov 27Dec 4
16°FNov 10Nov 15Nov 19Nov 22Nov 26Nov 30Dec 3Dec 7Dec 14

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°F174168162158154150145140134
32°F193186181177173169164160152
28°F213208203199195190186182174
24°F236228224220216212208203195
20°F260253246242238232227222214
16°F280272266261256252246240232

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
6,001
Cooling degree days, base 65°F
1,029
Growing degree days, base 40°F
5,652
Growing degree days, base 45°F
4,477
Growing degree days, base 50°F
3,432
Growing degree days, base 55°F
2,503
Growing degree days, base 60°F
1,701

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27101
February1,03203
March805234
April43710131
May16083396
June21227655
July3313775
August7255713
September81122493
October36019192
November727136
December1,09703

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 18.9 km from Roanoke. 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 USC00115712 (Minonk). Public domain.