Carson City climate

Carson City Frost Dates and Growing Season

NOAA 1991-2020 normals for Alma, 28.3 km from Carson City, elevation 729 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Alma. 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 1 and the first fall freeze around October 13, a growing season of about 164 days.

Median at 36°F
last May 14, first October 2
Median at 32°F
last May 1, first October 13
Median at 28°F
last April 20, first October 28

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°FMay 29May 25May 21May 17May 14May 10May 6May 3Apr 29
32°FMay 19May 13May 8May 5May 1Apr 29Apr 25Apr 22Apr 17
28°FMay 6Apr 30Apr 25Apr 22Apr 20Apr 17Apr 13Apr 10Apr 4
24°FApr 21Apr 17Apr 14Apr 10Apr 7Apr 4Apr 2Mar 31Mar 25
20°FApr 10Apr 6Apr 3Apr 1Mar 31Mar 27Mar 23Mar 20Mar 14
16°FApr 2Mar 31Mar 27Mar 23Mar 20Mar 17Mar 15Mar 11Mar 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 20Sep 24Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15
32°FSep 29Oct 3Oct 7Oct 10Oct 13Oct 17Oct 20Oct 24Oct 30
28°FOct 10Oct 17Oct 21Oct 24Oct 28Oct 30Nov 1Nov 4Nov 9
24°FOct 25Oct 30Nov 1Nov 4Nov 6Nov 9Nov 13Nov 16Nov 21
20°FNov 4Nov 8Nov 13Nov 16Nov 19Nov 22Nov 26Nov 30Dec 6
16°FNov 13Nov 19Nov 24Nov 28Dec 1Dec 4Dec 8Dec 13Dec 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°F159153148144140136132127121
32°F184178172168164160156150141
28°F211204198193188184179174165
24°F235227222218214210206201194
20°F259250244239234230225221214
16°F279271266260255251247242234

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
7,051
Cooling degree days, base 65°F
544
Growing degree days, base 40°F
4,489
Growing degree days, base 45°F
3,439
Growing degree days, base 50°F
2,519
Growing degree days, base 55°F
1,726
Growing degree days, base 60°F
1,060

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33100
February1,15600
March992013
April596256
May27731249
June61116506
July14192643
August25147587
September16149347
October4795106
November817011
December1,14100

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 28.3 km from Carson City. 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 USC00200146 (Alma). Public domain.