Boyce climate

Boyce Frost Dates and Growing Season

NOAA 1991-2020 normals for Winchester, 13.3 km from Boyce, elevation 720 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Winchester. 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 29, a growing season of about 200 days.

Median at 36°F
last April 23, first October 18
Median at 32°F
last April 11, first October 29
Median at 28°F
last March 31, first November 9

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 11May 5May 1Apr 27Apr 23Apr 20Apr 17Apr 14Apr 9
32°FApr 29Apr 21Apr 17Apr 14Apr 11Apr 8Apr 5Apr 3Mar 30
28°FApr 12Apr 8Apr 4Apr 2Mar 31Mar 28Mar 24Mar 20Mar 15
24°FApr 2Mar 30Mar 26Mar 22Mar 18Mar 16Mar 12Mar 8Mar 2
20°FMar 23Mar 18Mar 14Mar 11Mar 8Mar 5Mar 2Feb 26Feb 18
16°FMar 15Mar 10Mar 5Mar 2Feb 27Feb 23Feb 17Feb 10Feb 1

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 9Oct 13Oct 15Oct 18Oct 20Oct 23Oct 26Oct 30
32°FOct 14Oct 19Oct 23Oct 26Oct 29Oct 31Nov 2Nov 6Nov 11
28°FOct 27Oct 31Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 25
24°FNov 4Nov 10Nov 14Nov 17Nov 21Nov 25Nov 29Dec 3Dec 10
20°FNov 16Nov 23Nov 28Dec 1Dec 5Dec 10Dec 15Dec 22Dec 28
16°FDec 1Dec 7Dec 12Dec 18Dec 23Dec 27Dec 31Jan 6Jan 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°F197190185181176172169164156
32°F221213208204200196191185178
28°F246239233228224220216211204
24°F271263257253248244239234226
20°F298289283278273267262257249
16°F325315307302297292287281271

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
4,915
Cooling degree days, base 65°F
1,050
Growing degree days, base 40°F
6,037
Growing degree days, base 45°F
4,738
Growing degree days, base 50°F
3,590
Growing degree days, base 55°F
2,592
Growing degree days, base 60°F
1,745

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00408
February83009
March696246
April35717177
May13869399
June19214645
July1334798
August3282744
September63118507
October32215198
November601149
December882012

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 13.3 km from Boyce. 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 USC00449181 (Winchester). Public domain.