Hebron climate

Hebron Frost Dates and Growing Season

NOAA 1991-2020 normals for Hebron, 1.1 km from Hebron, elevation 1480 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hebron. 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 15, a growing season of about 172 days.

Median at 36°F
last May 2, first October 5
Median at 32°F
last April 24, first October 15
Median at 28°F
last April 13, first October 23

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 14May 10May 7May 4May 2Apr 30Apr 29Apr 25Apr 20
32°FMay 5May 2Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 9
28°FApr 27Apr 22Apr 19Apr 16Apr 13Apr 10Apr 6Apr 3Mar 30
24°FApr 21Apr 15Apr 11Apr 7Apr 4Apr 1Mar 30Mar 25Mar 18
20°FApr 12Apr 6Apr 2Mar 30Mar 26Mar 22Mar 18Mar 14Mar 8
16°FApr 3Mar 28Mar 24Mar 19Mar 15Mar 11Mar 7Mar 4Feb 28

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 21Sep 27Sep 30Oct 3Oct 5Oct 8Oct 12Oct 14Oct 18
32°FSep 29Oct 4Oct 8Oct 12Oct 15Oct 17Oct 19Oct 22Oct 26
28°FOct 6Oct 14Oct 18Oct 20Oct 23Oct 26Oct 29Nov 1Nov 4
24°FOct 17Oct 22Oct 26Oct 30Nov 1Nov 3Nov 6Nov 9Nov 15
20°FOct 24Oct 30Nov 1Nov 5Nov 8Nov 11Nov 15Nov 20Nov 25
16°FOct 31Nov 5Nov 10Nov 14Nov 17Nov 21Nov 24Nov 28Dec 3

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°F171165161157154150146143136
32°F190184180176172168164159153
28°F212204199195191187183178172
24°F231223217214209205200195187
20°F249241235230226222218212203
16°F270261255250245241235228220

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
5,931
Cooling degree days, base 65°F
1,150
Growing degree days, base 40°F
5,794
Growing degree days, base 45°F
4,609
Growing degree days, base 50°F
3,556
Growing degree days, base 55°F
2,624
Growing degree days, base 60°F
1,822

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22300
February99704
March764141
April4328135
May17167373
June17245678
July1372835
August5307767
September86133500
October36917192
November755130
December1,11101

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 1.1 km from Hebron. 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 USC00253735 (Hebron). Public domain.