Harrison climate

Harrison Frost Dates and Growing Season

NOAA 1991-2020 normals for Harrison, 3.8 km from Harrison, elevation 1132 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Harrison. 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 March 22 and the first fall freeze around November 9, a growing season of about 231 days.

Median at 36°F
last April 3, first October 28
Median at 32°F
last March 22, first November 9
Median at 28°F
last March 7, first November 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°FApr 22Apr 15Apr 10Apr 7Apr 3Mar 31Mar 28Mar 23Mar 16
32°FApr 8Apr 2Mar 30Mar 25Mar 22Mar 17Mar 13Mar 8Mar 1
28°FMar 27Mar 20Mar 15Mar 11Mar 7Mar 3Feb 28Feb 23Feb 17
24°FMar 16Mar 9Mar 4Feb 28Feb 25Feb 21Feb 16Feb 8Jan 31
20°FMar 5Feb 27Feb 21Feb 16Feb 10Feb 4Jan 31Jan 23Jan 12
16°FFeb 26Feb 18Feb 10Feb 3Jan 30Jan 24Jan 16Jan 9Dec 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°FOct 13Oct 19Oct 23Oct 25Oct 28Oct 31Nov 3Nov 6Nov 13
32°FOct 25Oct 31Nov 2Nov 6Nov 9Nov 13Nov 17Nov 22Nov 28
28°FNov 2Nov 8Nov 13Nov 18Nov 23Nov 26Dec 1Dec 5Dec 12
24°FNov 12Nov 22Nov 27Dec 1Dec 5Dec 10Dec 15Dec 22Dec 30
20°FNov 27Dec 5Dec 12Dec 18Dec 24Dec 29Jan 3Jan 10Jan 19
16°FDec 7Dec 15Dec 22Dec 29Jan 2Jan 8Jan 13Jan 20Feb 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°F232222216212208204199193186
32°F256248242236231227221215208
28°F283275268262255250244237229
24°F315305297289283276271263254
20°F346336329321314307301292280
16°F365365355346338332323314303

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
97% of years
16°F or colder
81% 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
3,822
Cooling degree days, base 65°F
1,537
Growing degree days, base 40°F
7,288
Growing degree days, base 45°F
5,820
Growing degree days, base 50°F
4,514
Growing degree days, base 55°F
3,362
Growing degree days, base 60°F
2,379

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January854015
February678033
March4884102
April22724270
May63121523
June1298746
July0429894
August0410875
September23192620
October21153325
November500694
December778018

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 3.8 km from Harrison. 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 USC00033164 (Harrison). Public domain.