Roanoke climate

Roanoke Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Wayne Intl AP, 14 km from Roanoke, elevation 791 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Wayne Intl AP. 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 178 days.

Median at 36°F
last May 4, first October 9
Median at 32°F
last April 24, first October 21
Median at 28°F
last April 12, first November 1

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 18May 13May 10May 7May 4May 1Apr 29Apr 26Apr 20
32°FMay 10May 5May 1Apr 28Apr 24Apr 21Apr 18Apr 15Apr 10
28°FApr 28Apr 22Apr 18Apr 15Apr 12Apr 8Apr 5Apr 2Mar 28
24°FApr 15Apr 9Apr 6Apr 3Mar 31Mar 29Mar 26Mar 21Mar 16
20°FApr 3Mar 31Mar 27Mar 24Mar 20Mar 17Mar 14Mar 10Mar 4
16°FMar 27Mar 21Mar 17Mar 14Mar 10Mar 8Mar 4Mar 1Feb 22

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 25Sep 30Oct 3Oct 6Oct 9Oct 12Oct 14Oct 17Oct 22
32°FOct 8Oct 12Oct 16Oct 18Oct 21Oct 23Oct 25Oct 29Nov 1
28°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11Nov 16
24°FNov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 23Nov 29
20°FNov 8Nov 12Nov 17Nov 21Nov 24Nov 28Dec 1Dec 6Dec 14
16°FNov 16Nov 23Nov 27Dec 1Dec 4Dec 8Dec 13Dec 19Dec 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°F176169164160156153149144138
32°F199192186182178174170165157
28°F222217211208203199195189182
24°F248240235230226221217212206
20°F272263258253249245240234227
16°F296286278273268264259252245

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
5,968
Cooling degree days, base 65°F
849
Growing degree days, base 40°F
5,398
Growing degree days, base 45°F
4,220
Growing degree days, base 50°F
3,178
Growing degree days, base 55°F
2,267
Growing degree days, base 60°F
1,489

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22402
February1,01503
March819127
April4527115
May17762359
June25194619
July3275738
August8212670
September9486445
October37612167
November717030
December1,05904

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 14 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 USW00014827 (Ft Wayne Intl AP). Public domain.