Washoe County climate

Washoe County Frost Dates and Growing Season

NOAA 1991-2020 normals for Smoke Creek Espil, 9.7 km from Washoe County, elevation 3850 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Smoke Creek Espil. 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 10 and the first fall freeze around October 1, a growing season of about 141 days.

Median at 36°F
last May 24, first September 19
Median at 32°F
last May 10, first October 1
Median at 28°F
last April 28, 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 13Jun 3May 31May 28May 24May 21May 18May 14May 10
32°FMay 29May 23May 18May 14May 10May 6May 3Apr 30Apr 24
28°FMay 16May 10May 4Apr 30Apr 28Apr 25Apr 21Apr 15Apr 7
24°FMay 7Apr 30Apr 24Apr 19Apr 14Apr 8Apr 4Mar 30Mar 21
20°FApr 22Apr 13Apr 6Apr 1Mar 27Mar 22Mar 17Mar 11Mar 1
16°FApr 6Mar 27Mar 17Mar 12Mar 6Mar 1Feb 24Feb 16Feb 4

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 4Sep 9Sep 13Sep 16Sep 19Sep 22Sep 25Sep 29Oct 4
32°FSep 15Sep 21Sep 25Sep 29Oct 1Oct 4Oct 7Oct 11Oct 15
28°FSep 30Oct 3Oct 7Oct 10Oct 13Oct 16Oct 20Oct 23Oct 29
24°FOct 10Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 2Nov 6
20°FOct 19Oct 24Oct 27Oct 31Nov 2Nov 5Nov 8Nov 12Nov 18
16°FOct 27Nov 1Nov 4Nov 8Nov 11Nov 15Nov 18Nov 21Nov 26

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°F13612912512011611210710189
32°F164157151146141137133127118
28°F191183176171166161157150143
24°F217209203198191186181175166
20°F245235228222216211205196186
16°F279268259253247241233224212

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
5,702
Cooling degree days, base 65°F
805
Growing degree days, base 40°F
5,109
Growing degree days, base 45°F
3,920
Growing degree days, base 50°F
2,914
Growing degree days, base 55°F
2,073
Growing degree days, base 60°F
1,374

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,01800
February79800
March674017
April494071
May26232262
June64136523
July6329789
August10240694
September9166428
October4132126
November78605
December1,08800

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 9.7 km from Washoe 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 USC00267618 (Smoke Creek Espil). Public domain.