Monterey climate

Monterey Frost Dates and Growing Season

NOAA 1991-2020 normals for Mustoe 1 Sw, 12.8 km from Monterey, elevation 2367 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mustoe 1 Sw. 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 8 and the first fall freeze around October 5, a growing season of about 148 days.

Median at 36°F
last May 21, first September 25
Median at 32°F
last May 8, first October 5
Median at 28°F
last April 29, first October 17

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 4May 31May 28May 24May 21May 17May 14May 10May 4
32°FMay 26May 20May 17May 13May 8May 5May 2Apr 29Apr 23
28°FMay 18May 12May 6May 2Apr 29Apr 25Apr 21Apr 18Apr 13
24°FMay 3Apr 23Apr 19Apr 16Apr 13Apr 10Apr 6Apr 3Mar 30
20°FApr 13Apr 7Apr 4Apr 1Mar 30Mar 27Mar 24Mar 19Mar 15
16°FApr 1Mar 28Mar 25Mar 21Mar 18Mar 14Mar 10Mar 6Mar 1

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 13Sep 17Sep 20Sep 22Sep 25Sep 27Sep 29Oct 2Oct 6
32°FSep 22Sep 27Oct 1Oct 3Oct 5Oct 8Oct 11Oct 14Oct 19
28°FOct 4Oct 8Oct 11Oct 14Oct 17Oct 20Oct 23Oct 26Oct 30
24°FOct 12Oct 18Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 9
20°FOct 23Oct 28Nov 1Nov 3Nov 5Nov 8Nov 11Nov 16Nov 24
16°FNov 1Nov 6Nov 11Nov 15Nov 18Nov 22Nov 27Dec 2Dec 6

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°F148141136131127124120116108
32°F167161156152148144139134128
28°F191184179175171166162155146
24°F215209205200196191186179170
20°F244236230225221217213208201
16°F271263256250246242237232224

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
6,140
Cooling degree days, base 65°F
310
Growing degree days, base 40°F
4,486
Growing degree days, base 45°F
3,320
Growing degree days, base 50°F
2,319
Growing degree days, base 55°F
1,475
Growing degree days, base 60°F
795

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12802
February94102
March817017
April494182
May25011248
June7159438
July22120563
August3493524
September15725324
October4612100
November748016
December1,01703

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 12.8 km from Monterey. 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 USC00445880 (Mustoe 1 Sw). Public domain.