Sterling climate

Sterling Frost Dates and Growing Season

NOAA 1991-2020 normals for Sterling 6SW, 9.9 km from Sterling, elevation 292 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sterling 6SW. 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 20 and the first fall freeze around September 21, a growing season of about 123 days.

Median at 36°F
last June 4, first September 8
Median at 32°F
last May 20, first September 21
Median at 28°F
last May 3, first September 30

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°FJun 15Jun 11Jun 8Jun 6Jun 4Jun 2May 31May 29May 25
32°FJun 1May 28May 25May 22May 20May 17May 14May 11May 6
28°FMay 17May 12May 9May 6May 3May 1Apr 29Apr 24Apr 19
24°FMay 2Apr 30Apr 26Apr 23Apr 19Apr 16Apr 13Apr 11Apr 7
20°FApr 25Apr 19Apr 15Apr 12Apr 9Apr 7Apr 5Apr 3Mar 31
16°FApr 18Apr 12Apr 8Apr 6Apr 4Apr 2Mar 31Mar 28Mar 23

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°FAug 26Aug 31Sep 2Sep 5Sep 8Sep 11Sep 14Sep 18Sep 23
32°FSep 6Sep 11Sep 15Sep 18Sep 21Sep 24Sep 26Sep 29Oct 4
28°FSep 17Sep 23Sep 25Sep 28Sep 30Oct 3Oct 6Oct 9Oct 15
24°FSep 29Oct 2Oct 5Oct 8Oct 11Oct 14Oct 16Oct 20Oct 25
20°FOct 5Oct 9Oct 14Oct 16Oct 20Oct 22Oct 25Oct 29Nov 5
16°FOct 12Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 5Nov 12

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°F112106101979491888377
32°F141135131127123119115111105
28°F169162157153148145141136128
24°F194187182178175171166161154
20°F212205201198194189185180173
16°F225219214209206202199194187

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
10,671
Cooling degree days, base 65°F
7
Growing degree days, base 40°F
1,913
Growing degree days, base 45°F
1,150
Growing degree days, base 50°F
570
Growing degree days, base 55°F
198
Growing degree days, base 60°F
46

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,55300
February1,26300
March1,27400
April84600
May592011
June3482123
July2343235
August2942178
September536023
October93900
November1,29800
December1,49400

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 9.9 km from Sterling. 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 USC00508731 (Sterling 6SW). Public domain.