The Lakes climate

The Lakes Frost Dates and Growing Season

NOAA 1991-2020 normals for Tracy, 11.6 km from The Lakes, elevation 1403 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tracy. 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 2 and the first fall freeze around October 5, a growing season of about 156 days.

Median at 36°F
last May 11, first September 27
Median at 32°F
last May 2, first October 5
Median at 28°F
last April 23, first October 15

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 26May 20May 16May 13May 11May 8May 6May 3Apr 30
32°FMay 15May 10May 6May 4May 2Apr 30Apr 27Apr 23Apr 18
28°FMay 5May 2Apr 29Apr 26Apr 23Apr 19Apr 16Apr 13Apr 8
24°FApr 28Apr 23Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Mar 31
20°FApr 19Apr 14Apr 11Apr 8Apr 5Apr 2Mar 31Mar 26Mar 20
16°FApr 13Apr 7Apr 4Apr 1Mar 29Mar 26Mar 21Mar 17Mar 13

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 14Sep 19Sep 22Sep 24Sep 27Sep 29Oct 2Oct 5Oct 10
32°FSep 22Sep 27Sep 30Oct 3Oct 5Oct 8Oct 12Oct 15Oct 20
28°FOct 1Oct 5Oct 9Oct 12Oct 15Oct 19Oct 22Oct 25Oct 28
24°FOct 8Oct 15Oct 20Oct 23Oct 25Oct 28Oct 30Nov 2Nov 8
20°FOct 21Oct 26Oct 29Nov 1Nov 3Nov 5Nov 9Nov 12Nov 18
16°FOct 29Nov 1Nov 5Nov 8Nov 11Nov 14Nov 17Nov 21Nov 27

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°F156150145142138135132127121
32°F174168165160156153149144138
28°F194187183179175172168162155
24°F214206201197194190186180173
20°F232225220215210206203198191
16°F249241236231227222216211203

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
8,026
Cooling degree days, base 65°F
647
Growing degree days, base 40°F
4,552
Growing degree days, base 45°F
3,544
Growing degree days, base 50°F
2,647
Growing degree days, base 55°F
1,860
Growing degree days, base 60°F
1,190

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57900
February1,30700
March1,07707
April632259
May26939274
June46149554
July12226679
August27162600
September16164365
October543698
November971011
December1,40100

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 11.6 km from The Lakes. 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 USC00218323 (Tracy). Public domain.