Merced County climate

Merced County Frost Dates and Growing Season

NOAA 1991-2020 normals for Merced 23 Wsw, 15.4 km from Merced County, elevation 78 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Merced 23 Wsw. 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 28 and the first fall freeze around November 14, a growing season of about 233 days.

Median at 36°F
last April 29, first October 31
Median at 32°F
last March 28, first November 14
Median at 28°F
last February 12, first November 29

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 25May 16May 10May 3Apr 29Apr 25Apr 19Apr 14Apr 6
32°FApr 27Apr 17Apr 10Apr 2Mar 28Mar 19Mar 7Feb 28Feb 18
28°FMar 24Mar 1Feb 24Feb 18Feb 12Feb 6Jan 29Jan 17Jan 4
24°FFeb 13Feb 3Jan 29Jan 20Jan 12Jan 5Dec 31Dec 25Dec 12
20°FJan 23Jan 16Jan 9Jan 4Dec 31Dec 26Dec 20Dec 15Dec 4
16°F–––––––––

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 9Oct 17Oct 23Oct 28Oct 31Nov 3Nov 6Nov 10Nov 16
32°FOct 27Nov 1Nov 6Nov 10Nov 14Nov 17Nov 21Nov 25Dec 1
28°FNov 9Nov 16Nov 21Nov 25Nov 29Dec 2Dec 7Dec 14Dec 31
24°FNov 22Nov 28Dec 1Dec 7Dec 12Dec 18Dec 26Jan 3Jan 12
20°FDec 1Dec 6Dec 12Dec 16Dec 21Dec 29Jan 1Jan 5Jan 13
16°F–––––––––

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°F211201194188183176168160150
32°F274260251242233225216207196
28°F333322312301294287278269253
24°F365364354346340334328320307
20°F365365365365365365360350338
16°F365365365365365365365365365

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
79% of years
20°F or colder
35% of years
16°F or colder
8% 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
2,909
Cooling degree days, base 65°F
980
Growing degree days, base 40°F
7,218
Growing degree days, base 45°F
5,510
Growing degree days, base 50°F
4,009
Growing degree days, base 55°F
2,756
Growing degree days, base 60°F
1,748

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January605012
February440046
March3460139
April2388226
May9455426
June19169600
July1301766
August1255719
September19158589
October12833371
November404095
December617018

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 15.4 km from Merced County. 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 USW00093243 (Merced 23 Wsw). Public domain.