Sunflower County climate

Sunflower County Frost Dates and Growing Season

NOAA 1991-2020 normals for Moorhead, 18.3 km from Sunflower County, elevation 117 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Moorhead. 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 8 and the first fall freeze around November 20, a growing season of about 255 days.

Median at 36°F
last March 22, first November 8
Median at 32°F
last March 8, first November 20
Median at 28°F
last February 25, first December 3

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 7Apr 2Mar 31Mar 26Mar 22Mar 18Mar 13Mar 9Mar 1
32°FMar 27Mar 20Mar 15Mar 11Mar 8Mar 4Feb 28Feb 24Feb 17
28°FMar 15Mar 9Mar 5Feb 28Feb 25Feb 20Feb 15Feb 8Jan 31
24°FMar 6Feb 26Feb 20Feb 13Feb 6Feb 1Jan 28Jan 22Jan 11
20°FFeb 21Feb 10Feb 3Jan 31Jan 27Jan 22Jan 15Jan 8Jan 1
16°FFeb 10Feb 3Jan 30Jan 26Jan 22Jan 18Jan 11Jan 5Jan 1

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 27Oct 31Nov 3Nov 5Nov 8Nov 11Nov 14Nov 18Nov 24
32°FNov 4Nov 8Nov 12Nov 16Nov 20Nov 24Nov 28Dec 2Dec 9
28°FNov 12Nov 19Nov 25Nov 30Dec 3Dec 7Dec 13Dec 23Jan 2
24°FNov 29Dec 6Dec 12Dec 21Dec 28Jan 1Jan 5Jan 12Jan 23
20°FDec 11Dec 24Dec 30Jan 2Jan 6Jan 12Jan 17Jan 24Feb 1
16°FDec 25Jan 1Jan 4Jan 9Jan 15Jan 18Jan 21Jan 29Feb 4

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°F257248243237232228224218211
32°F281272266260255251246239231
28°F318306299292284278271263254
24°F352338331324318310303293281
20°F365365362354346338333325311
16°F365365365365365365358347334

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
96% of years
20°F or colder
73% of years
16°F or colder
36% 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
2,601
Cooling degree days, base 65°F
2,354
Growing degree days, base 40°F
9,050
Growing degree days, base 45°F
7,433
Growing degree days, base 50°F
5,947
Growing degree days, base 55°F
4,599
Growing degree days, base 60°F
3,401

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January663156
February489487
March31021231
April11086432
May16254704
June0430880
July0527992
August0525990
September4357802
October92127505
November34316187
December575581

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 18.3 km from Sunflower County. 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 USC00226009 (Moorhead). Public domain.