Oglala climate

Oglala Frost Dates and Growing Season

NOAA 1991-2020 normals for Oglala 1S, 1.6 km from Oglala, elevation 2995 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oglala 1S. 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 7 and the first fall freeze around October 4, a growing season of about 149 days.

Median at 36°F
last May 17, first September 26
Median at 32°F
last May 7, first October 4
Median at 28°F
last April 27, first October 16

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 29May 25May 23May 20May 17May 14May 12May 8May 5
32°FMay 21May 16May 13May 9May 7May 4May 1Apr 29Apr 24
28°FMay 11May 5May 2Apr 30Apr 27Apr 24Apr 21Apr 17Apr 12
24°FApr 30Apr 26Apr 22Apr 19Apr 15Apr 12Apr 9Apr 5Mar 31
20°FApr 21Apr 16Apr 12Apr 8Apr 5Apr 2Mar 30Mar 25Mar 19
16°FApr 13Apr 7Apr 3Mar 31Mar 26Mar 22Mar 19Mar 12Mar 6

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 12Sep 17Sep 21Sep 24Sep 26Sep 29Oct 1Oct 4Oct 8
32°FSep 21Sep 26Sep 30Oct 2Oct 4Oct 7Oct 10Oct 14Oct 19
28°FOct 1Oct 5Oct 9Oct 13Oct 16Oct 18Oct 21Oct 24Oct 28
24°FOct 9Oct 15Oct 18Oct 22Oct 24Oct 26Oct 29Nov 1Nov 6
20°FOct 17Oct 22Oct 25Oct 28Nov 1Nov 3Nov 6Nov 10Nov 16
16°FOct 24Oct 28Nov 1Nov 5Nov 9Nov 12Nov 16Nov 20Nov 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°F148142137134130126122117110
32°F167161157153149145141136128
28°F189182177173169165161157150
24°F211202198193189186181175168
20°F230223217212208203198193187
16°F254243236231226221215208200

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
6,623
Cooling degree days, base 65°F
815
Growing degree days, base 40°F
4,968
Growing degree days, base 45°F
3,843
Growing degree days, base 50°F
2,874
Growing degree days, base 55°F
2,049
Growing degree days, base 60°F
1,364

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22400
February1,01502
March826026
April553174
May28122245
June63129517
July7304762
August16265714
September13887410
October4945111
November839013
December1,16701

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 1.6 km from Oglala. 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 USC00396227 (Oglala 1S). Public domain.