Herriman climate

Herriman Frost Dates and Growing Season

NOAA 1991-2020 normals for Utah Lake Lehi, 20.6 km from Herriman, elevation 4505 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Utah Lake Lehi. 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 9, a growing season of about 159 days.

Median at 36°F
last May 20, first September 28
Median at 32°F
last April 30, first October 9
Median at 28°F
last April 15, first October 22

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 13Jun 5May 31May 25May 20May 16May 11May 5Apr 30
32°FMay 27May 16May 8May 4Apr 30Apr 28Apr 24Apr 20Apr 14
28°FMay 2Apr 26Apr 22Apr 19Apr 15Apr 11Apr 7Apr 3Mar 28
24°FApr 16Apr 11Apr 7Apr 3Mar 30Mar 23Mar 16Mar 10Mar 4
20°FApr 5Mar 26Mar 15Mar 8Mar 4Mar 1Feb 25Feb 20Feb 13
16°FMar 10Mar 2Feb 26Feb 22Feb 17Feb 13Feb 8Feb 3Jan 29

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 16Sep 20Sep 23Sep 26Sep 28Oct 1Oct 4Oct 7Oct 13
32°FSep 26Sep 29Oct 2Oct 6Oct 9Oct 12Oct 16Oct 19Oct 25
28°FOct 5Oct 11Oct 15Oct 19Oct 22Oct 25Oct 28Nov 1Nov 6
24°FOct 16Oct 23Oct 27Oct 31Nov 2Nov 4Nov 7Nov 11Nov 16
20°FOct 28Nov 3Nov 6Nov 9Nov 12Nov 16Nov 19Nov 23Nov 27
16°FNov 6Nov 12Nov 16Nov 20Nov 24Nov 26Nov 29Dec 4Dec 11

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°F156148143137131126120112104
32°F182174169164159154149143131
28°F211203197191187183178172163
24°F246236229223217212206199191
20°F277268262256250244236227217
16°F306296289283279273268261252

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
5,955
Cooling degree days, base 65°F
788
Growing degree days, base 40°F
5,039
Growing degree days, base 45°F
3,883
Growing degree days, base 50°F
2,887
Growing degree days, base 55°F
2,044
Growing degree days, base 60°F
1,345

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,13100
February86501
March710011
April485166
May24516253
June51116515
July2331793
August4272733
September11252394
October4461110
November816010
December1,08600

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 20.6 km from Herriman. 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 USC00428973 (Utah Lake Lehi). Public domain.