Howard County climate

Howard County Frost Dates and Growing Season

NOAA 1991-2020 normals for Saint Paul, 4.9 km from Howard County, elevation 1812 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Saint Paul. 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 23 and the first fall freeze around October 14, a growing season of about 172 days.

Median at 36°F
last May 3, first October 4
Median at 32°F
last April 23, first October 14
Median at 28°F
last April 13, first October 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°FMay 16May 11May 8May 6May 3May 1Apr 29Apr 25Apr 21
32°FMay 7May 2Apr 29Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10
28°FApr 27Apr 22Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Mar 31
24°FApr 18Apr 13Apr 9Apr 7Apr 4Apr 1Mar 30Mar 26Mar 19
20°FApr 10Apr 5Apr 2Mar 30Mar 27Mar 23Mar 19Mar 14Mar 8
16°FApr 2Mar 29Mar 24Mar 20Mar 16Mar 12Mar 8Mar 4Feb 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°FSep 22Sep 27Sep 30Oct 2Oct 4Oct 7Oct 9Oct 12Oct 16
32°FSep 28Oct 3Oct 6Oct 10Oct 14Oct 17Oct 19Oct 22Oct 26
28°FOct 7Oct 14Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1Nov 5
24°FOct 17Oct 23Oct 27Oct 30Nov 1Nov 4Nov 6Nov 9Nov 15
20°FOct 26Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 20Nov 25
16°FNov 2Nov 7Nov 12Nov 15Nov 20Nov 23Nov 26Nov 29Dec 5

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°F170164160157154150146142136
32°F190184180176172168164158151
28°F211204200196192187183178170
24°F232225220215212208203197190
20°F253244238233228223219214207
16°F269261256251246241235229221

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
5,955
Cooling degree days, base 65°F
1,129
Growing degree days, base 40°F
5,775
Growing degree days, base 45°F
4,592
Growing degree days, base 50°F
3,532
Growing degree days, base 55°F
2,601
Growing degree days, base 60°F
1,798

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24400
February99502
March743037
April41411141
May15861376
June19234664
July2370834
August5309769
September77131507
October37113182
November783021
December1,14400

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 4.9 km from Howard County. 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 USC00257515 (Saint Paul). Public domain.