Cassia County climate

Cassia County Frost Dates and Growing Season

NOAA 1991-2020 normals for Malta, 19.2 km from Cassia County, elevation 4521 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Malta. 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 June 5 and the first fall freeze around September 13, a growing season of about 96 days.

Median at 32°F
last June 5, first September 13
Median at 28°F
last May 17, first September 26

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°F–––––––––
32°FJun 23Jun 16Jun 13Jun 9Jun 5Jun 3May 31May 25May 19
28°FJun 4May 30May 25May 21May 17May 13May 9May 5Apr 30
24°FMay 19May 13May 8May 5May 2Apr 28Apr 23Apr 18Apr 12
20°FMay 6Apr 29Apr 23Apr 19Apr 15Apr 11Apr 6Apr 1Mar 25
16°FApr 16Apr 11Apr 5Apr 1Mar 29Mar 24Mar 18Mar 11Mar 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°F–––––––––
32°FAug 28Sep 2Sep 6Sep 9Sep 13Sep 16Sep 20Sep 23Sep 28
28°FSep 8Sep 15Sep 20Sep 24Sep 26Sep 29Oct 3Oct 6Oct 13
24°FSep 23Sep 28Oct 1Oct 4Oct 7Oct 12Oct 15Oct 19Oct 26
20°FOct 2Oct 8Oct 14Oct 18Oct 22Oct 25Oct 29Nov 2Nov 7
16°FOct 18Oct 24Oct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 20

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°F918479736964605346
32°F1191121061019692868173
28°F153144139134129124119113104
24°F184175169164159154148142133
20°F217206201195189183178171162
16°F250239232226221215209202193

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
7,122
Cooling degree days, base 65°F
280
Growing degree days, base 40°F
3,770
Growing degree days, base 45°F
2,727
Growing degree days, base 50°F
1,873
Growing degree days, base 55°F
1,187
Growing degree days, base 60°F
656

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,18700
February95500
March82802
April628023
May4002125
June17226311
July36129558
August42105529
September22118267
October566055
November89303
December1,19500

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 19.2 km from Cassia 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 USC00105567 (Malta). Public domain.