Mona climate

Mona Frost Dates and Growing Season

NOAA 1991-2020 normals for Nephi, 11.7 km from Mona, elevation 5146 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Nephi. 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 6 and the first fall freeze around October 10, a growing season of about 156 days.

Median at 36°F
last May 20, first September 30
Median at 32°F
last May 6, first October 10
Median at 28°F
last April 21, first October 23

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 7Jun 1May 28May 24May 20May 17May 13May 9May 3
32°FMay 24May 18May 13May 9May 6May 2Apr 30Apr 27Apr 21
28°FMay 9May 3Apr 29Apr 25Apr 21Apr 18Apr 14Apr 10Apr 4
24°FApr 24Apr 15Apr 10Apr 6Apr 2Mar 30Mar 25Mar 19Mar 12
20°FApr 3Mar 28Mar 21Mar 16Mar 12Mar 8Mar 4Feb 28Feb 22
16°FMar 14Mar 8Mar 4Mar 1Feb 25Feb 22Feb 18Feb 14Feb 6

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 18Sep 22Sep 25Sep 28Sep 30Oct 2Oct 5Oct 8Oct 13
32°FSep 28Oct 1Oct 4Oct 7Oct 10Oct 13Oct 16Oct 20Oct 24
28°FOct 7Oct 12Oct 16Oct 19Oct 23Oct 25Oct 28Nov 1Nov 5
24°FOct 17Oct 23Oct 26Oct 31Nov 2Nov 5Nov 8Nov 12Nov 16
20°FOct 26Nov 2Nov 6Nov 9Nov 12Nov 16Nov 19Nov 23Nov 29
16°FNov 5Nov 11Nov 15Nov 19Nov 22Nov 25Nov 29Dec 2Dec 8

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°F151144138134130126121115109
32°F177170164160156152146140132
28°F207198192187182177171165157
24°F237228222217212207202196183
20°F268259253248243237231224214
16°F293284278273269264257251243

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
6,077
Cooling degree days, base 65°F
821
Growing degree days, base 40°F
5,076
Growing degree days, base 45°F
3,918
Growing degree days, base 50°F
2,928
Growing degree days, base 55°F
2,092
Growing degree days, base 60°F
1,392

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,13600
February88901
March715020
April523167
May27121247
June66132518
July2325787
August5266725
September10375428
October4392121
November791014
December1,13700

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 11.7 km from Mona. 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 USC00426135 (Nephi). Public domain.