Parowan climate

Parowan Frost Dates and Growing Season

NOAA 1991-2020 normals for Cedar City 5E, 25.2 km from Parowan, elevation 6465 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cedar City 5E. 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 23 and the first fall freeze around October 4, a growing season of about 130 days.

Median at 36°F
last June 3, first September 25
Median at 32°F
last May 23, first October 4
Median at 28°F
last May 8, first October 13

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 17Jun 12Jun 7Jun 5Jun 3Jun 1May 29May 25May 20
32°FJun 8Jun 3May 31May 27May 23May 19May 16May 12May 5
28°FMay 27May 21May 16May 12May 8May 4Apr 30Apr 27Apr 21
24°FMay 14May 7May 1Apr 28Apr 23Apr 19Apr 15Apr 11Apr 5
20°FApr 26Apr 17Apr 12Apr 8Apr 5Apr 1Mar 28Mar 21Mar 14
16°FApr 6Mar 31Mar 24Mar 19Mar 15Mar 10Mar 7Mar 3Feb 25

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 16Sep 19Sep 22Sep 25Sep 27Sep 29Oct 3Oct 7
32°FSep 20Sep 24Sep 28Oct 1Oct 4Oct 7Oct 10Oct 14Oct 18
28°FSep 29Oct 3Oct 6Oct 10Oct 13Oct 16Oct 19Oct 23Oct 27
24°FOct 7Oct 13Oct 16Oct 20Oct 24Oct 27Oct 30Nov 3Nov 9
20°FOct 18Oct 23Oct 27Oct 31Nov 3Nov 6Nov 10Nov 14Nov 19
16°FOct 24Nov 1Nov 5Nov 8Nov 13Nov 16Nov 20Nov 24Nov 29

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°F1291231181141101061029791
32°F153145140134130126121116110
28°F178171165160155150145139131
24°F206198191186181177172165157
20°F236226219214209204199192183
16°F266256250244239232226218209

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
6,136
Cooling degree days, base 65°F
429
Growing degree days, base 40°F
4,513
Growing degree days, base 45°F
3,361
Growing degree days, base 50°F
2,392
Growing degree days, base 55°F
1,590
Growing degree days, base 60°F
931

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,04200
February88200
March774010
April570046
May3357186
June9665422
July8180637
August11143597
September12534367
October4531112
November770015
December1,06900

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 25.2 km from Parowan. 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 USC00421260 (Cedar City 5E). Public domain.