Hennessey climate

Hennessey Frost Dates and Growing Season

NOAA 1991-2020 normals for Hennessey 4 Ese, 6 km from Hennessey, elevation 1174 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hennessey 4 Ese. 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 14 and the first fall freeze around October 30, a growing season of about 198 days.

Median at 36°F
last April 23, first October 21
Median at 32°F
last April 14, first October 30
Median at 28°F
last April 2, first November 6

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 5May 1Apr 28Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10
32°FApr 27Apr 23Apr 20Apr 17Apr 14Apr 10Apr 7Apr 2Mar 29
28°FApr 18Apr 13Apr 9Apr 6Apr 2Mar 31Mar 27Mar 22Mar 13
24°FApr 7Apr 2Mar 29Mar 24Mar 20Mar 15Mar 11Mar 6Feb 28
20°FMar 28Mar 19Mar 14Mar 10Mar 6Mar 3Feb 28Feb 24Feb 15
16°FMar 14Mar 7Mar 3Feb 28Feb 25Feb 21Feb 16Feb 9Jan 31

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 6Oct 11Oct 15Oct 18Oct 21Oct 23Oct 26Oct 29Nov 2
32°FOct 17Oct 21Oct 25Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11
28°FOct 25Oct 29Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 22
24°FOct 31Nov 5Nov 8Nov 11Nov 14Nov 18Nov 21Nov 26Dec 1
20°FNov 6Nov 12Nov 17Nov 21Nov 25Nov 28Dec 2Dec 7Dec 14
16°FNov 16Nov 23Nov 28Dec 1Dec 6Dec 10Dec 16Dec 22Jan 1

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°F200192187184180176173168162
32°F220213207202198194190186178
28°F242234228222218213209204197
24°F265255249244238233227221213
20°F287279272267262256251244234
16°F316306298292287280274266257

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
4,146
Cooling degree days, base 65°F
1,868
Growing degree days, base 40°F
7,429
Growing degree days, base 45°F
6,025
Growing degree days, base 50°F
4,778
Growing degree days, base 55°F
3,669
Growing degree days, base 60°F
2,701

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91606
February728020
March535396
April26921238
May68135532
June2379826
July05411,006
August0485950
September22253681
October20348332
November542281
December860010

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 6 km from Hennessey. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00344055 (Hennessey 4 Ese). Public domain.