Boone climate

Boone Frost Dates and Growing Season

NOAA 1991-2020 normals for Boone, 2.2 km from Boone, elevation 1035 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boone. 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 28 and the first fall freeze around October 12, a growing season of about 165 days.

Median at 36°F
last May 7, first October 1
Median at 32°F
last April 28, first October 12
Median at 28°F
last April 16, first October 22

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 22May 17May 13May 10May 7May 4May 2Apr 30Apr 25
32°FMay 11May 6May 3Apr 30Apr 28Apr 24Apr 21Apr 18Apr 13
28°FApr 30Apr 26Apr 22Apr 19Apr 16Apr 13Apr 10Apr 7Apr 3
24°FApr 22Apr 16Apr 12Apr 9Apr 6Apr 4Apr 1Mar 28Mar 22
20°FApr 13Apr 6Apr 2Mar 31Mar 28Mar 24Mar 20Mar 16Mar 11
16°FApr 2Mar 29Mar 25Mar 22Mar 18Mar 14Mar 11Mar 7Mar 2

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

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°F164157152149145142139134127
32°F185179173170165161157152146
28°F207200195191187183179174167
24°F227220215211207203199194186
20°F249241236232227223217212205
16°F270261255250245241237231223

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
6,921
Cooling degree days, base 65°F
799
Growing degree days, base 40°F
5,075
Growing degree days, base 45°F
3,982
Growing degree days, base 50°F
3,005
Growing degree days, base 55°F
2,144
Growing degree days, base 60°F
1,406

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,43700
February1,16801
March901121
April505598
May20947321
June30169590
July5267727
August12213666
September12087423
October44511140
November845018
December1,24601

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 2.2 km from Boone. 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 USC00130807 (Boone). Public domain.