Southmayd climate

Southmayd Frost Dates and Growing Season

NOAA 1991-2020 normals for Sherman, 14.3 km from Southmayd, elevation 760 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sherman. 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 14 and the first fall freeze around November 19, a growing season of about 250 days.

Median at 36°F
last March 28, first November 9
Median at 32°F
last March 14, first November 19
Median at 28°F
last March 2, first November 30

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 15Apr 8Apr 4Mar 31Mar 28Mar 24Mar 19Mar 15Mar 8
32°FApr 1Mar 27Mar 22Mar 18Mar 14Mar 10Mar 6Mar 2Feb 25
28°FMar 21Mar 14Mar 10Mar 6Mar 2Feb 28Feb 24Feb 18Feb 10
24°FMar 13Mar 5Mar 1Feb 25Feb 20Feb 14Feb 8Jan 31Jan 22
20°FMar 4Feb 25Feb 18Feb 12Feb 6Jan 31Jan 25Jan 16Jan 2
16°FFeb 24Feb 14Feb 7Feb 1Jan 25Jan 17Jan 10Jan 1Dec 22

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 26Oct 31Nov 3Nov 6Nov 9Nov 12Nov 15Nov 20Nov 24
32°FNov 2Nov 8Nov 12Nov 16Nov 19Nov 22Nov 26Dec 1Dec 6
28°FNov 11Nov 18Nov 22Nov 26Nov 30Dec 3Dec 7Dec 12Dec 20
24°FNov 23Nov 30Dec 4Dec 8Dec 14Dec 21Dec 26Jan 1Jan 8
20°FDec 4Dec 10Dec 17Dec 24Dec 31Jan 3Jan 9Jan 18Feb 1
16°FDec 11Dec 18Dec 26Jan 1Jan 5Jan 12Jan 18Feb 1Feb 9

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°F251242236231225221215209201
32°F276266261256250245239234225
28°F301291284279274268262255247
24°F331320311306300294288280269
20°F363349338332326320311304293
16°F365365365362353346335327313

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
93% of years
16°F or colder
67% 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
2,727
Cooling degree days, base 65°F
2,261
Growing degree days, base 40°F
8,858
Growing degree days, base 45°F
7,245
Growing degree days, base 50°F
5,765
Growing degree days, base 55°F
4,437
Growing degree days, base 60°F
3,267

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January675144
February502278
March32417215
April12758388
May23203645
June0419868
July05581,023
August05531,018
September7330772
October100106477
November35112178
December617258

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 14.3 km from Southmayd. 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 USC00418274 (Sherman). Public domain.