Tracy climate

Tracy Frost Dates and Growing Season

NOAA 1991-2020 normals for Tracy Carbona, 9.5 km from Tracy, elevation 135 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tracy Carbona. 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 February 25 and the first fall freeze around November 26, a growing season of about 272 days.

Median at 36°F
last April 3, first November 12
Median at 32°F
last February 25, first November 26
Median at 28°F
last January 18, first December 11

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 23Apr 17Apr 12Apr 8Apr 3Mar 31Mar 22Mar 11Feb 28
32°FApr 6Mar 28Mar 9Mar 1Feb 25Feb 19Feb 12Feb 5Jan 24
28°FFeb 21Feb 11Feb 2Jan 27Jan 18Jan 12Jan 6Jan 1Dec 26
24°FFeb 4Jan 18Jan 11Jan 6Jan 3Dec 31Dec 28Dec 24Dec 16
20°FFeb 5Jan 21Jan 6Jan 4Dec 31Dec 29Dec 27Dec 21Dec 11
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 26Nov 1Nov 5Nov 9Nov 12Nov 15Nov 18Nov 21Nov 26
32°FNov 8Nov 16Nov 20Nov 23Nov 26Nov 29Dec 2Dec 6Dec 12
28°FNov 25Dec 1Dec 4Dec 8Dec 11Dec 16Dec 21Dec 27Jan 4
24°FDec 5Dec 12Dec 16Dec 21Dec 24Dec 29Jan 1Jan 6Jan 14
20°FDec 8Dec 16Dec 24Dec 27Dec 30Jan 2Jan 5Jan 19Feb 3
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°F257244236227222216210203193
32°F306296286278272265253240228
28°F354346339334327319311301287
24°F365365365363359355349342333
20°F365365365365365365365365357
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
95% of years
24°F or colder
58% of years
20°F or colder
16% of years
16°F or colder
1% 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
2,583
Cooling degree days, base 65°F
1,129
Growing degree days, base 40°F
7,684
Growing degree days, base 45°F
5,931
Growing degree days, base 50°F
4,362
Growing degree days, base 55°F
3,043
Growing degree days, base 60°F
1,970

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January564019
February406062
March3171162
April18915279
May7384476
June11209648
July1308772
August0275739
September9189630
October9548419
November3401135
December578022

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 9.5 km from Tracy. 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 USC00048999 (Tracy Carbona). Public domain.