Susanville climate

Susanville Frost Dates and Growing Season

NOAA 1991-2020 normals for Susanville 2SW, 0.9 km from Susanville, elevation 4212 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Susanville 2SW. 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 16 and the first fall freeze around October 8, a growing season of about 143 days.

Median at 36°F
last June 4, first September 26
Median at 32°F
last May 16, first October 8
Median at 28°F
last April 26, first October 21

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 18Jun 14Jun 10Jun 7Jun 4Jun 2May 30May 24May 18
32°FJun 5May 31May 24May 20May 16May 12May 8May 3Apr 29
28°FMay 17May 8May 2Apr 30Apr 26Apr 22Apr 18Apr 12Apr 7
24°FApr 28Apr 20Apr 16Apr 11Apr 6Apr 3Mar 31Mar 25Mar 17
20°FApr 9Apr 1Mar 26Mar 20Mar 15Mar 10Mar 6Mar 1Feb 20
16°FMar 15Mar 8Mar 3Feb 27Feb 23Feb 18Feb 11Feb 4Jan 25

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 12Sep 17Sep 20Sep 23Sep 26Sep 29Oct 1Oct 4Oct 8
32°FSep 25Sep 30Oct 3Oct 5Oct 8Oct 10Oct 13Oct 17Oct 22
28°FOct 5Oct 9Oct 13Oct 17Oct 21Oct 24Oct 27Oct 31Nov 3
24°FOct 15Oct 22Oct 27Oct 31Nov 2Nov 5Nov 8Nov 11Nov 17
20°FOct 27Nov 3Nov 8Nov 11Nov 14Nov 17Nov 21Nov 25Dec 1
16°FNov 7Nov 13Nov 18Nov 22Nov 26Nov 30Dec 3Dec 9Dec 16

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°F1351261211181141091059992
32°F167158153148143138134127118
28°F201193187182176171165159151
24°F234225218213208203196191182
20°F271260253247241236230222211
16°F311298290283276271264256244

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
5,834
Cooling degree days, base 65°F
456
Growing degree days, base 40°F
4,551
Growing degree days, base 45°F
3,361
Growing degree days, base 50°F
2,376
Growing degree days, base 55°F
1,579
Growing degree days, base 60°F
944

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00800
February79501
March716010
April535049
May3268184
June12058394
July17188637
August20153598
September11747385
October4222112
November75007
December1,00900

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 0.9 km from Susanville. 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 USC00048702 (Susanville 2SW). Public domain.