Harold climate

Harold Frost Dates and Growing Season

NOAA 1991-2020 normals for Whiting Fld Nas, 14.6 km from Harold, elevation 199 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Whiting Fld Nas. 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 14 and the first fall freeze around November 19, a growing season of about 251 days.

Median at 36°F
last March 28, first November 7
Median at 32°F
last March 14, first November 19
Median at 28°F
last February 28, first December 2

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 14Apr 8Apr 5Apr 1Mar 28Mar 23Mar 19Mar 14Mar 5
32°FApr 4Mar 29Mar 23Mar 17Mar 14Mar 9Mar 5Feb 28Feb 21
28°FMar 21Mar 15Mar 9Mar 4Feb 28Feb 22Feb 16Feb 9Jan 31
24°FMar 12Mar 2Feb 24Feb 17Feb 10Feb 2Jan 28Jan 19Jan 5
20°FMar 1Feb 20Feb 8Jan 31Jan 26Jan 19Jan 13Jan 4Dec 25
16°FFeb 20Feb 3Jan 28Jan 22Jan 15Jan 10Jan 5Dec 30Dec 21

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 26Oct 30Nov 2Nov 5Nov 7Nov 11Nov 14Nov 18Nov 25
32°FNov 4Nov 8Nov 12Nov 16Nov 19Nov 23Nov 27Dec 1Dec 8
28°FNov 12Nov 17Nov 23Nov 28Dec 2Dec 7Dec 13Dec 24Jan 4
24°FNov 25Dec 4Dec 10Dec 20Dec 27Jan 1Jan 7Jan 15Jan 30
20°FDec 9Dec 21Dec 28Jan 1Jan 6Jan 13Jan 18Jan 26Feb 8
16°FDec 14Dec 26Dec 31Jan 3Jan 9Jan 15Jan 22Jan 28Feb 9

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°F254244236230225220215209201
32°F280270262257251247240234225
28°F318306297289283275267260249
24°F359342333324313306299290277
20°F365365365360350341332321306
16°F365365365365365365365354334

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
92% of years
20°F or colder
64% of years
16°F or colder
31% 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
1,721
Cooling degree days, base 65°F
2,342
Growing degree days, base 40°F
9,780
Growing degree days, base 45°F
8,031
Growing degree days, base 50°F
6,379
Growing degree days, base 55°F
4,867
Growing degree days, base 60°F
3,514

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4546127
February31611169
March20034316
April6988471
May7259716
June0421871
July0490955
August0477942
September1364813
October56147558
November23531270
December38413171

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 14.6 km from Harold. 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 USW00093841 (Whiting Fld Nas). Public domain.