Tooele County climate

Tooele County Frost Dates and Growing Season

NOAA 1991-2020 normals for Dugway, 34.4 km from Tooele County, elevation 4345 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dugway. 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 11 and the first fall freeze around October 2, a growing season of about 143 days.

Median at 36°F
last May 23, first September 24
Median at 32°F
last May 11, first October 2
Median at 28°F
last April 28, first October 12

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 8Jun 2May 30May 26May 23May 20May 17May 13May 8
32°FMay 29May 22May 18May 15May 11May 7May 4Apr 30Apr 25
28°FMay 17May 10May 5May 2Apr 28Apr 24Apr 20Apr 15Apr 9
24°FMay 3Apr 26Apr 21Apr 16Apr 12Apr 7Apr 3Mar 29Mar 21
20°FApr 15Apr 8Apr 2Mar 28Mar 24Mar 19Mar 13Mar 8Mar 2
16°FMar 31Mar 23Mar 15Mar 9Mar 5Mar 2Feb 27Feb 21Feb 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 10Sep 15Sep 19Sep 21Sep 24Sep 27Sep 29Oct 1Oct 5
32°FSep 19Sep 24Sep 27Sep 30Oct 2Oct 5Oct 7Oct 11Oct 15
28°FSep 28Oct 2Oct 6Oct 8Oct 12Oct 15Oct 17Oct 21Oct 25
24°FOct 7Oct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1Nov 7
20°FOct 18Oct 23Oct 27Oct 31Nov 3Nov 7Nov 11Nov 15Nov 20
16°FOct 27Nov 2Nov 7Nov 11Nov 15Nov 19Nov 22Nov 26Dec 1

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°F142135130126122118114109101
32°F162156151147143138133128119
28°F188180175170164160156151142
24°F217208201196191185180173165
20°F249239232227222216210203195
16°F281271264258252246239233223

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
5,911
Cooling degree days, base 65°F
1,087
Growing degree days, base 40°F
5,463
Growing degree days, base 45°F
4,275
Growing degree days, base 50°F
3,262
Growing degree days, base 55°F
2,405
Growing degree days, base 60°F
1,688

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,14400
February84601
March685020
April470285
May22430288
June44186593
July2415879
August4357818
September9094459
October4422113
November80408
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 34.4 km from Tooele County. 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 USC00422257 (Dugway). Public domain.