Dorris climate

Dorris Frost Dates and Growing Season

NOAA 1991-2020 normals for Keno, 14.2 km from Dorris, elevation 4128 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Keno. 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 June 5 and the first fall freeze around September 20, a growing season of about 107 days.

Median at 36°F
last June 21, first September 8
Median at 32°F
last June 5, first September 20
Median at 28°F
last May 14, first October 4

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°FJul 8Jul 1Jun 26Jun 23Jun 21Jun 18Jun 15Jun 10Jun 5
32°FJun 22Jun 17Jun 13Jun 9Jun 5Jun 2May 30May 24May 16
28°FJun 7May 30May 23May 17May 14May 10May 6May 3Apr 29
24°FMay 14May 5May 1Apr 28Apr 26Apr 23Apr 19Apr 15Apr 9
20°FApr 23Apr 16Apr 11Apr 8Apr 5Mar 31Mar 27Mar 20Mar 12
16°FApr 4Mar 27Mar 21Mar 14Mar 10Mar 4Feb 28Feb 19Feb 11

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 24Aug 30Sep 2Sep 5Sep 8Sep 10Sep 13Sep 16Sep 19
32°FSep 6Sep 11Sep 14Sep 17Sep 20Sep 23Sep 25Sep 29Oct 4
28°FSep 19Sep 24Sep 28Oct 1Oct 4Oct 6Oct 10Oct 14Oct 20
24°FOct 3Oct 8Oct 12Oct 15Oct 19Oct 23Oct 27Nov 1Nov 8
20°FOct 17Oct 24Oct 29Nov 1Nov 4Nov 8Nov 13Nov 19Nov 25
16°FNov 1Nov 7Nov 12Nov 17Nov 21Nov 25Nov 29Dec 4Dec 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°F989186827874696352
32°F129121116111107102989284
28°F167157153147142136130123114
24°F200193186182178173168162152
20°F244233225219213208203196187
16°F290278269262255247240232223

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
6,631
Cooling degree days, base 65°F
285
Growing degree days, base 40°F
3,821
Growing degree days, base 45°F
2,759
Growing degree days, base 50°F
1,912
Growing degree days, base 55°F
1,229
Growing degree days, base 60°F
680

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,05300
February85500
March80301
April633022
May3923135
June19240314
July35137567
August3086521
September18919293
October546157
November83502
December1,06900

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 14.2 km from Dorris. 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 USC00354403 (Keno). Public domain.