Emmett climate

Emmett Frost Dates and Growing Season

NOAA 1991-2020 normals for Emmett 2 E, 3.4 km from Emmett, elevation 2390 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Emmett 2 E. 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 30 and the first fall freeze around October 17, a growing season of about 168 days.

Median at 36°F
last May 16, first October 4
Median at 32°F
last April 30, first October 17
Median at 28°F
last April 14, first October 28

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 5May 30May 24May 19May 16May 12May 8May 5May 1
32°FMay 17May 11May 7May 3Apr 30Apr 29Apr 26Apr 22Apr 17
28°FMay 3Apr 28Apr 23Apr 18Apr 14Apr 10Apr 6Mar 31Mar 26
24°FApr 9Apr 4Mar 31Mar 26Mar 19Mar 13Mar 8Mar 2Feb 25
20°FMar 15Mar 7Mar 2Feb 28Feb 24Feb 20Feb 16Feb 10Jan 31
16°FFeb 28Feb 23Feb 17Feb 12Feb 7Feb 1Jan 24Jan 13Jan 3

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 20Sep 26Sep 29Oct 2Oct 4Oct 6Oct 10Oct 13Oct 18
32°FOct 2Oct 7Oct 11Oct 14Oct 17Oct 19Oct 22Oct 25Nov 1
28°FOct 15Oct 19Oct 22Oct 25Oct 28Oct 31Nov 4Nov 8Nov 13
24°FOct 24Oct 29Nov 2Nov 7Nov 10Nov 13Nov 17Nov 21Nov 26
20°FNov 1Nov 8Nov 13Nov 18Nov 22Nov 25Nov 29Dec 3Dec 12
16°FNov 11Nov 21Nov 26Dec 1Dec 3Dec 8Dec 15Dec 23Jan 3

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°F163156150144140135130124118
32°F190182176172168163159153146
28°F224215209202197193188181173
24°F263253246239233226221214206
20°F303291283277271266261254244
16°F335324315308302294286279267

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
99% 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
5,689
Cooling degree days, base 65°F
789
Growing degree days, base 40°F
5,112
Growing degree days, base 45°F
3,895
Growing degree days, base 50°F
2,871
Growing degree days, base 55°F
2,023
Growing degree days, base 60°F
1,333

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06000
February80402
March656018
April472174
May24525264
June83101469
July9308764
August12274727
September10877421
October4184123
November77508
December1,04802

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 3.4 km from Emmett. 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 USC00102942 (Emmett 2 E). Public domain.