Garretson climate

Garretson Frost Dates and Growing Season

NOAA 1991-2020 normals for Sioux Falls 14 Nne, 9.8 km from Garretson, elevation 1594 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sioux Falls 14 Nne. 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 1 and the first fall freeze around October 4, a growing season of about 155 days.

Median at 36°F
last May 10, first September 26
Median at 32°F
last May 1, first October 4
Median at 28°F
last April 23, 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 24May 19May 15May 12May 10May 7May 5May 2Apr 28
32°FMay 15May 9May 6May 4May 1Apr 29Apr 27Apr 23Apr 16
28°FMay 6May 2Apr 29Apr 26Apr 23Apr 19Apr 15Apr 12Apr 6
24°FApr 28Apr 23Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 29
20°FApr 20Apr 13Apr 9Apr 6Apr 3Apr 1Mar 29Mar 23Mar 17
16°FApr 12Apr 5Apr 2Mar 30Mar 26Mar 22Mar 18Mar 15Mar 10

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 13Sep 17Sep 20Sep 23Sep 26Sep 28Oct 1Oct 3Oct 8
32°FSep 21Sep 25Sep 28Oct 1Oct 4Oct 6Oct 10Oct 15Oct 19
28°FSep 29Oct 3Oct 7Oct 12Oct 15Oct 18Oct 21Oct 24Oct 28
24°FOct 10Oct 16Oct 20Oct 23Oct 25Oct 28Oct 31Nov 3Nov 6
20°FOct 21Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17
16°FOct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 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°F156150145141138134131126121
32°F174168163159155151147143137
28°F196188183179175171167162154
24°F215208203199195190185180172
20°F233225221216212207203199192
16°F249241236232227223218213206

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
7,788
Cooling degree days, base 65°F
594
Growing degree days, base 40°F
4,546
Growing degree days, base 45°F
3,524
Growing degree days, base 50°F
2,608
Growing degree days, base 55°F
1,807
Growing degree days, base 60°F
1,132

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,54000
February1,26400
March1,013010
April591266
May25134275
June41135544
July9215671
August25153593
September16450347
October537496
November96905
December1,38200

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 9.8 km from Garretson. 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 USW00004990 (Sioux Falls 14 Nne). Public domain.