El Dorado County climate

El Dorado County Frost Dates and Growing Season

NOAA 1991-2020 normals for Pacific House, 3 km from El Dorado County, elevation 3450 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pacific House. 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 April 26 and the first fall freeze around November 2, a growing season of about 191 days.

Median at 36°F
last May 20, first October 16
Median at 32°F
last April 26, first November 2
Median at 28°F
last April 6, first November 22

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 9Jun 3May 31May 26May 20May 14May 8May 3Apr 29
32°FMay 19May 9May 2Apr 29Apr 26Apr 22Apr 19Apr 16Apr 10
28°FApr 24Apr 17Apr 13Apr 9Apr 6Apr 3Mar 30Mar 22Mar 10
24°FApr 4Mar 27Mar 18Mar 11Mar 5Feb 28Feb 19Feb 8Jan 22
20°FMar 7Mar 1Feb 23Feb 13Feb 5Jan 24Jan 12Jan 2Dec 20
16°FFeb 23Feb 11Jan 30Jan 16Jan 7Jan 2Dec 27Dec 19Dec 10

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 30Oct 5Oct 10Oct 13Oct 16Oct 19Oct 24Oct 29Nov 4
32°FOct 14Oct 20Oct 24Oct 30Nov 2Nov 6Nov 10Nov 15Nov 20
28°FOct 31Nov 9Nov 15Nov 18Nov 22Nov 26Dec 1Dec 5Dec 11
24°FNov 19Nov 27Dec 1Dec 6Dec 10Dec 15Dec 20Dec 28Jan 12
20°FDec 4Dec 13Dec 20Dec 28Jan 1Jan 6Jan 18Feb 6Feb 21
16°FDec 9Dec 17Dec 22Dec 30Jan 3Jan 10Jan 20Jan 31Feb 15

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°F178170162156151145139132122
32°F214207201196191184178171162
28°F262249242235230225219212202
24°F325309298289280273266255243
20°F365365361350338326315304293
16°F365365365365365365365361339

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
99% of years
20°F or colder
77% of years
16°F or colder
26% 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
4,977
Cooling degree days, base 65°F
594
Growing degree days, base 40°F
5,152
Growing degree days, base 45°F
3,853
Growing degree days, base 50°F
2,775
Growing degree days, base 55°F
1,889
Growing degree days, base 60°F
1,168

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January84000
February68506
March642028
April471080
May25513243
June9377439
July6218677
August4177639
September72100482
October36610161
November664020
December88000

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 3 km from El Dorado County. 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 USC00046597 (Pacific House). Public domain.