Clearwater climate

Clearwater Frost Dates and Growing Season

NOAA 1991-2020 normals for Haysville 3SE, 16.8 km from Clearwater, elevation 1240 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Haysville 3SE. 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 April 14 and the first fall freeze around October 22, a growing season of about 189 days.

Median at 36°F
last April 24, first October 12
Median at 32°F
last April 14, first October 22
Median at 28°F
last April 3, first October 31

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 7May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14Apr 10
32°FApr 30Apr 24Apr 21Apr 17Apr 14Apr 12Apr 8Apr 4Mar 30
28°FApr 19Apr 14Apr 9Apr 6Apr 3Mar 31Mar 28Mar 24Mar 16
24°FApr 9Apr 4Mar 31Mar 28Mar 24Mar 20Mar 15Mar 10Mar 4
20°FMar 30Mar 23Mar 18Mar 14Mar 10Mar 7Mar 3Feb 28Feb 23
16°FMar 17Mar 12Mar 8Mar 4Mar 1Feb 27Feb 23Feb 17Feb 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 27Oct 2Oct 6Oct 9Oct 12Oct 15Oct 18Oct 21Oct 25
32°FOct 5Oct 12Oct 16Oct 19Oct 22Oct 24Oct 27Oct 30Nov 4
28°FOct 16Oct 21Oct 25Oct 27Oct 31Nov 2Nov 5Nov 9Nov 15
24°FOct 25Oct 30Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 26
20°FNov 1Nov 6Nov 11Nov 15Nov 19Nov 22Nov 26Dec 1Dec 5
16°FNov 9Nov 16Nov 21Nov 25Nov 29Dec 3Dec 6Dec 11Dec 19

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°F189182177173169165160155148
32°F210203197193189183179174166
28°F231224218213208204199193186
24°F257247241236231226221215206
20°F278270264259253248242235227
16°F299292285279274268263256247

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
4,605
Cooling degree days, base 65°F
1,631
Growing degree days, base 40°F
6,945
Growing degree days, base 45°F
5,600
Growing degree days, base 50°F
4,403
Growing degree days, base 55°F
3,350
Growing degree days, base 60°F
2,429

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,01502
February798013
March585476
April29425232
May90121499
June4338784
July0475939
August1422886
September40206617
October25139288
November593263
December93504

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 16.8 km from Clearwater. 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 USC00143545 (Haysville 3SE). Public domain.