Emery County climate

Emery County Frost Dates and Growing Season

NOAA 1991-2020 normals for Castle Dale, 35.7 km from Emery County, elevation 5629 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Castle Dale. 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 18 and the first fall freeze around September 27, a growing season of about 128 days.

Median at 36°F
last June 3, first September 18
Median at 32°F
last May 18, first September 27
Median at 28°F
last May 4, first October 5

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 19Jun 14Jun 10Jun 6Jun 3May 31May 28May 23May 19
32°FJun 8May 31May 26May 22May 18May 15May 12May 8May 4
28°FMay 20May 14May 10May 7May 4May 2Apr 29Apr 26Apr 22
24°FMay 6May 2Apr 28Apr 25Apr 23Apr 20Apr 17Apr 14Apr 9
20°FApr 24Apr 19Apr 15Apr 11Apr 8Apr 5Apr 2Mar 29Mar 22
16°FApr 11Apr 4Mar 31Mar 27Mar 21Mar 16Mar 12Mar 7Mar 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 4Sep 9Sep 12Sep 15Sep 18Sep 20Sep 23Sep 26Sep 28
32°FSep 14Sep 19Sep 22Sep 25Sep 27Sep 29Oct 1Oct 5Oct 9
28°FSep 25Sep 28Oct 1Oct 3Oct 5Oct 8Oct 12Oct 16Oct 20
24°FOct 2Oct 7Oct 11Oct 15Oct 18Oct 21Oct 23Oct 27Nov 1
20°FOct 14Oct 20Oct 23Oct 26Oct 29Nov 1Nov 2Nov 5Nov 9
16°FOct 23Oct 28Nov 1Nov 3Nov 6Nov 9Nov 11Nov 15Nov 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°F124118113109105101969286
32°F149142137132128125120115108
28°F171166161157153149145141133
24°F194188184179175172169164157
20°F222215210205200196192187179
16°F251244237233227222218213206

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
6,378
Cooling degree days, base 65°F
547
Growing degree days, base 40°F
4,673
Growing degree days, base 45°F
3,547
Growing degree days, base 50°F
2,574
Growing degree days, base 55°F
1,755
Growing degree days, base 60°F
1,078

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23800
February93800
March72709
April503056
May25710238
June5893485
July3243705
August6174632
September11927362
October468085
November85502
December1,20600

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 35.7 km from Emery County. 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 USC00421214 (Castle Dale). Public domain.