Ponca climate

Ponca Frost Dates and Growing Season

NOAA 1991-2020 normals for Vermillion 2 Se, 28.2 km from Ponca, elevation 1137 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Vermillion 2 Se. 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 May 3 and the first fall freeze around October 3, a growing season of about 153 days.

Median at 36°F
last May 11, first September 25
Median at 32°F
last May 3, first October 3
Median at 28°F
last April 24, first October 15

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 25May 20May 16May 14May 11May 9May 7May 4Apr 30
32°FMay 16May 12May 9May 5May 3Apr 30Apr 28Apr 25Apr 20
28°FMay 9May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 10
24°FApr 28Apr 23Apr 20Apr 17Apr 14Apr 10Apr 7Apr 3Mar 30
20°FApr 20Apr 14Apr 10Apr 7Apr 4Apr 2Mar 29Mar 24Mar 18
16°FApr 10Apr 5Apr 2Mar 30Mar 26Mar 22Mar 19Mar 14Mar 9

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 11Sep 16Sep 19Sep 22Sep 25Sep 28Sep 30Oct 3Oct 7
32°FSep 20Sep 24Sep 28Oct 1Oct 3Oct 6Oct 9Oct 13Oct 17
28°FSep 29Oct 3Oct 7Oct 11Oct 15Oct 18Oct 21Oct 23Oct 27
24°FOct 9Oct 15Oct 19Oct 22Oct 24Oct 27Oct 29Nov 1Nov 5
20°FOct 20Oct 25Oct 28Oct 31Nov 1Nov 4Nov 6Nov 10Nov 14
16°FOct 29Nov 2Nov 4Nov 7Nov 10Nov 13Nov 15Nov 19Nov 25

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°F152147142138135131129124118
32°F171165160157153149145140133
28°F192185180175171167163158151
24°F212204200196192188183178170
20°F231224219214209206202197190
16°F251243238233229224219213206

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
6,758
Cooling degree days, base 65°F
904
Growing degree days, base 40°F
5,269
Growing degree days, base 45°F
4,158
Growing degree days, base 50°F
3,160
Growing degree days, base 55°F
2,280
Growing degree days, base 60°F
1,527

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,38400
February1,11801
March875126
April4909110
May20158340
June27197619
July6295755
August12229682
September104102453
October43013155
November849020
December1,26200

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 28.2 km from Ponca. 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 USC00398622 (Vermillion 2 Se). Public domain.