Hartington climate

Hartington Frost Dates and Growing Season

NOAA 1991-2020 normals for Hartington, 0.7 km from Hartington, elevation 1408 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hartington. 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 30 and the first fall freeze around October 5, a growing season of about 159 days.

Median at 36°F
last May 8, first September 29
Median at 32°F
last April 30, first October 5
Median at 28°F
last April 20, first October 17

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 22May 17May 14May 11May 8May 6May 3May 1Apr 27
32°FMay 13May 9May 5May 3Apr 30Apr 28Apr 25Apr 21Apr 17
28°FMay 3Apr 30Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10Apr 7
24°FApr 24Apr 20Apr 16Apr 13Apr 10Apr 8Apr 5Apr 2Mar 28
20°FApr 16Apr 12Apr 8Apr 5Apr 2Mar 31Mar 27Mar 23Mar 16
16°FApr 9Apr 4Mar 31Mar 28Mar 24Mar 21Mar 18Mar 13Mar 8

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 14Sep 19Sep 23Sep 26Sep 29Oct 1Oct 3Oct 6Oct 11
32°FSep 21Sep 27Oct 1Oct 3Oct 5Oct 9Oct 12Oct 15Oct 20
28°FOct 1Oct 6Oct 9Oct 13Oct 17Oct 20Oct 23Oct 25Oct 29
24°FOct 9Oct 16Oct 21Oct 23Oct 26Oct 28Oct 31Nov 2Nov 7
20°FOct 21Oct 26Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17
16°FOct 29Nov 2Nov 5Nov 8Nov 11Nov 13Nov 17Nov 21Nov 28

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°F159153149145142138134129122
32°F179172168163159155151146139
28°F198191186183179175171166158
24°F216210206202198195190184177
20°F236228223218215211207202196
16°F254245239235231227222216210

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
7,025
Cooling degree days, base 65°F
811
Growing degree days, base 40°F
5,012
Growing degree days, base 45°F
3,929
Growing degree days, base 50°F
2,959
Growing degree days, base 55°F
2,114
Growing degree days, base 60°F
1,399

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,38900
February1,14701
March918119
April541483
May22947305
June34173589
July6285744
August14213663
September12782411
October4698126
November879016
December1,27200

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 0.7 km from Hartington. 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 USC00253630 (Hartington). Public domain.