Brookings climate

Brookings Frost Dates and Growing Season

NOAA 1991-2020 normals for Brookings 2 Ne, 2.8 km from Brookings, elevation 1639 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brookings 2 Ne. 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 6 and the first fall freeze around October 1, a growing season of about 145 days.

Median at 36°F
last May 15, first September 22
Median at 32°F
last May 6, first October 1
Median at 28°F
last April 28, first October 8

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 21May 18May 15May 13May 10May 7May 3
32°FMay 19May 14May 11May 9May 6May 4May 2Apr 29Apr 25
28°FMay 10May 5May 2Apr 30Apr 28Apr 24Apr 21Apr 18Apr 13
24°FMay 2Apr 28Apr 24Apr 20Apr 17Apr 14Apr 12Apr 8Apr 3
20°FApr 23Apr 18Apr 14Apr 10Apr 8Apr 5Apr 2Mar 30Mar 22
16°FApr 14Apr 9Apr 6Apr 2Mar 31Mar 27Mar 23Mar 18Mar 13

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 6Sep 12Sep 16Sep 19Sep 22Sep 25Sep 28Oct 1Oct 5
32°FSep 17Sep 22Sep 25Sep 29Oct 1Oct 3Oct 5Oct 9Oct 13
28°FSep 25Sep 30Oct 2Oct 5Oct 8Oct 12Oct 15Oct 19Oct 24
24°FOct 3Oct 8Oct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 2
20°FOct 18Oct 22Oct 26Oct 28Oct 31Nov 1Nov 4Nov 7Nov 12
16°FOct 26Oct 30Nov 2Nov 4Nov 6Nov 9Nov 13Nov 15Nov 20

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°F145139134131127124120116109
32°F163156152148145141137134127
28°F183177172168164160156151145
24°F205199194190185180176171164
20°F225217212208203199195190182
16°F241233229225220216211206198

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
8,378
Cooling degree days, base 65°F
524
Growing degree days, base 40°F
4,240
Growing degree days, base 45°F
3,260
Growing degree days, base 50°F
2,395
Growing degree days, base 55°F
1,643
Growing degree days, base 60°F
1,015

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,61700
February1,34000
March1,10106
April658147
May30425233
June65111497
July18196643
August36140569
September19548321
October595373
November1,01306
December1,43800

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 2.8 km from Brookings. 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 USC00391076 (Brookings 2 Ne). Public domain.