Shandon climate

Shandon Frost Dates and Growing Season

NOAA 1991-2020 normals for Paso Robles Muni AP, 22.9 km from Shandon, elevation 810 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Paso Robles Muni AP. 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 4 and the first fall freeze around November 5, a growing season of about 213 days.

Median at 36°F
last April 29, first October 21
Median at 32°F
last April 4, first November 5
Median at 28°F
last February 22, first November 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°FMay 17May 9May 4Apr 30Apr 29Apr 25Apr 21Apr 16Apr 10
32°FApr 27Apr 21Apr 14Apr 9Apr 4Mar 31Mar 25Mar 15Mar 2
28°FMar 31Mar 20Mar 8Feb 28Feb 22Feb 14Feb 7Jan 30Jan 13
24°FFeb 22Feb 9Feb 2Jan 28Jan 19Jan 7Dec 31Dec 25Dec 11
20°FJan 28Jan 14Jan 6Jan 1Dec 29Dec 25Dec 20Dec 15Dec 5
16°FJan 9Jan 1Dec 30Dec 26Dec 23Dec 19Dec 14Dec 12Dec 9

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 5Oct 10Oct 15Oct 18Oct 21Oct 25Oct 29Nov 1Nov 7
32°FOct 17Oct 23Oct 29Nov 1Nov 5Nov 9Nov 13Nov 18Nov 24
28°FNov 1Nov 7Nov 13Nov 17Nov 21Nov 25Nov 30Dec 4Dec 12
24°FNov 16Nov 24Nov 30Dec 2Dec 6Dec 10Dec 15Dec 26Jan 13
20°FDec 1Dec 2Dec 6Dec 11Dec 15Dec 19Dec 26Jan 1Jan 11
16°FDec 5Dec 8Dec 11Dec 14Dec 18Dec 22Dec 26Dec 29Jan 1

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°F201192186181175171165159151
32°F251237226220213208201193183
28°F315300290280274265254244230
24°F365352341335329321312302286
20°F365365365365365360350340331
16°F365365365365365365365365363

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
99% of years
24°F or colder
86% of years
20°F or colder
40% of years
16°F or colder
11% 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
2,760
Cooling degree days, base 65°F
959
Growing degree days, base 40°F
7,334
Growing degree days, base 45°F
5,583
Growing degree days, base 50°F
4,015
Growing degree days, base 55°F
2,731
Growing degree days, base 60°F
1,722

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January526032
February417059
March3570135
April2437222
May10856414
June26150575
July4264725
August2269732
September20170600
October13141376
November3661122
December563023

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 22.9 km from Shandon. 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 USW00093209 (Paso Robles Muni AP). Public domain.