Nevada County climate

Nevada County Frost Dates and Growing Season

NOAA 1991-2020 normals for Prescott 2 Nnw, 18.9 km from Nevada County, elevation 308 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Prescott 2 Nnw. 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 March 29 and the first fall freeze around November 6, a growing season of about 224 days.

Median at 36°F
last April 11, first October 28
Median at 32°F
last March 29, first November 6
Median at 28°F
last March 14, first November 16

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°FApr 27Apr 22Apr 18Apr 14Apr 11Apr 8Apr 5Apr 1Mar 26
32°FApr 15Apr 8Apr 4Apr 1Mar 29Mar 25Mar 20Mar 15Mar 9
28°FMar 31Mar 26Mar 21Mar 17Mar 14Mar 10Mar 6Mar 1Feb 24
24°FMar 18Mar 12Mar 8Mar 4Feb 28Feb 25Feb 21Feb 14Feb 4
20°FMar 7Mar 1Feb 24Feb 17Feb 10Feb 5Jan 31Jan 23Jan 13
16°FFeb 26Feb 12Feb 6Jan 31Jan 28Jan 21Jan 16Jan 9Dec 31

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°FOct 15Oct 19Oct 22Oct 25Oct 28Oct 31Nov 1Nov 4Nov 9
32°FOct 23Oct 30Nov 1Nov 3Nov 6Nov 8Nov 12Nov 17Nov 22
28°FNov 1Nov 5Nov 8Nov 12Nov 16Nov 19Nov 24Nov 29Dec 4
24°FNov 8Nov 14Nov 20Nov 24Nov 29Dec 1Dec 6Dec 12Dec 22
20°FNov 21Nov 29Dec 4Dec 10Dec 17Dec 23Dec 29Jan 3Jan 11
16°FDec 8Dec 20Dec 26Dec 31Jan 3Jan 7Jan 12Jan 17Jan 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°F223216210206202197192187180
32°F248240235229224219215208203
28°F271262257252247242237231222
24°F304292285278272266261254244
20°F340329321314306299291283270
16°F365361351344337331325316303

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
98% of years
16°F or colder
85% 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
3,055
Cooling degree days, base 65°F
1,944
Growing degree days, base 40°F
8,242
Growing degree days, base 45°F
6,676
Growing degree days, base 50°F
5,262
Growing degree days, base 55°F
3,998
Growing degree days, base 60°F
2,892

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January729133
February552256
March37110176
April15246352
May30176611
June0374823
July0493958
August0479944
September10282721
October14073407
November4128136
December658147

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 18.9 km from Nevada 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 USC00035908 (Prescott 2 Nnw). Public domain.