Council climate

Council Frost Dates and Growing Season

NOAA 1991-2020 normals for Council, 1.6 km from Council, elevation 2943 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Council. 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 10 and the first fall freeze around October 2, a growing season of about 145 days.

Median at 36°F
last June 1, first September 19
Median at 32°F
last May 10, first October 2
Median at 28°F
last April 22, first October 16

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 21Jun 14Jun 9Jun 5Jun 1May 27May 22May 17May 11
32°FJun 1May 23May 16May 13May 10May 6May 2Apr 29Apr 25
28°FMay 8May 2Apr 29Apr 26Apr 22Apr 18Apr 14Apr 10Apr 4
24°FApr 26Apr 17Apr 9Apr 5Mar 31Mar 29Mar 24Mar 17Mar 12
20°FApr 3Mar 28Mar 23Mar 16Mar 13Mar 9Mar 5Mar 2Feb 25
16°FMar 18Mar 12Mar 8Mar 5Mar 2Feb 28Feb 25Feb 20Feb 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 4Sep 10Sep 13Sep 16Sep 19Sep 22Sep 25Sep 29Oct 3
32°FSep 16Sep 24Sep 28Oct 1Oct 2Oct 5Oct 8Oct 13Oct 18
28°FOct 1Oct 5Oct 9Oct 13Oct 16Oct 18Oct 21Oct 25Oct 30
24°FOct 12Oct 17Oct 21Oct 24Oct 27Oct 31Nov 3Nov 8Nov 13
20°FOct 23Oct 29Nov 1Nov 5Nov 9Nov 12Nov 16Nov 21Nov 27
16°FNov 2Nov 8Nov 12Nov 17Nov 21Nov 24Nov 28Dec 1Dec 7

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°F133125119113109103989282
32°F166159154149145141133126116
28°F200192186181176170165159153
24°F235226219213208203197188179
20°F264255249243238234228221210
16°F290281275268263258252246238

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
6,454
Cooling degree days, base 65°F
729
Growing degree days, base 40°F
4,750
Growing degree days, base 45°F
3,633
Growing degree days, base 50°F
2,684
Growing degree days, base 55°F
1,891
Growing degree days, base 60°F
1,239

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21800
February96000
March76105
April512056
May26317239
June10282432
July10308762
August15263713
September12558386
October479289
November85002
December1,15800

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 1.6 km from Council. 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 USC00102187 (Council). Public domain.