McKenzie climate

McKenzie Frost Dates and Growing Season

NOAA 1991-2020 normals for Evergreen, 25 km from McKenzie, elevation 290 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Evergreen. 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 March 13 and the first fall freeze around November 19, a growing season of about 253 days.

Median at 36°F
last March 28, first November 6
Median at 32°F
last March 13, first November 19
Median at 28°F
last February 28, first December 3

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°FApr 15Apr 8Apr 5Mar 31Mar 28Mar 24Mar 19Mar 14Mar 7
32°FMar 31Mar 25Mar 21Mar 17Mar 13Mar 8Mar 3Feb 26Feb 18
28°FMar 21Mar 14Mar 8Mar 3Feb 28Feb 22Feb 16Feb 8Jan 31
24°FMar 11Mar 1Feb 24Feb 16Feb 9Feb 2Jan 30Jan 22Jan 6
20°FFeb 27Feb 14Feb 3Jan 31Jan 27Jan 21Jan 14Jan 6Dec 25
16°FFeb 11Feb 3Jan 31Jan 25Jan 19Jan 14Jan 9Jan 3Dec 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°FOct 24Oct 30Nov 1Nov 4Nov 6Nov 9Nov 13Nov 18Nov 25
32°FNov 2Nov 7Nov 11Nov 15Nov 19Nov 23Nov 28Dec 2Dec 9
28°FNov 11Nov 18Nov 23Nov 28Dec 3Dec 7Dec 13Dec 24Jan 3
24°FNov 23Dec 2Dec 8Dec 17Dec 24Jan 1Jan 5Jan 13Jan 26
20°FDec 8Dec 20Dec 27Jan 1Jan 7Jan 12Jan 18Jan 27Feb 2
16°FDec 21Dec 31Jan 3Jan 8Jan 12Jan 18Jan 24Feb 1Feb 8

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°F254243237231227221216210203
32°F280271264259253247240233225
28°F315304295289281274267259250
24°F356339332323315307301292279
20°F365365365360349339332322306
16°F365365365365365365364350333

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
94% of years
20°F or colder
69% of years
16°F or colder
32% 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
2,105
Cooling degree days, base 65°F
2,224
Growing degree days, base 40°F
9,320
Growing degree days, base 45°F
7,621
Growing degree days, base 50°F
6,044
Growing degree days, base 55°F
4,610
Growing degree days, base 60°F
3,328

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January534498
February3878128
March23932288
April9781437
May15241691
June0404853
July0487952
August0473938
September2339787
October78126516
November28523228
December4688127

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 25 km from McKenzie. 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 USC00012758 (Evergreen). Public domain.