Davis climate

Davis Frost Dates and Growing Season

NOAA 1991-2020 normals for Freeport Waste Wtp, 21 km from Davis, elevation 750 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Freeport Waste Wtp. 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 April 26 and the first fall freeze around October 13, a growing season of about 169 days.

Median at 36°F
last May 6, first October 3
Median at 32°F
last April 26, first October 13
Median at 28°F
last April 14, first October 24

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 21May 16May 12May 8May 6May 3May 1Apr 27Apr 22
32°FMay 11May 6May 2Apr 30Apr 26Apr 23Apr 19Apr 16Apr 11
28°FApr 30Apr 25Apr 21Apr 17Apr 14Apr 11Apr 7Apr 4Mar 31
24°FApr 19Apr 13Apr 9Apr 6Apr 3Apr 1Mar 30Mar 25Mar 18
20°FApr 7Apr 3Mar 31Mar 28Mar 24Mar 20Mar 16Mar 12Mar 7
16°FMar 31Mar 25Mar 20Mar 17Mar 14Mar 11Mar 8Mar 4Feb 28

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 22Sep 26Sep 29Oct 1Oct 3Oct 5Oct 8Oct 10Oct 15
32°FSep 30Oct 4Oct 8Oct 11Oct 13Oct 16Oct 18Oct 21Oct 26
28°FOct 10Oct 15Oct 19Oct 21Oct 24Oct 27Oct 29Nov 1Nov 5
24°FOct 22Oct 27Oct 31Nov 1Nov 4Nov 7Nov 10Nov 14Nov 20
20°FNov 1Nov 5Nov 9Nov 12Nov 15Nov 18Nov 22Nov 25Nov 30
16°FNov 8Nov 14Nov 17Nov 21Nov 24Nov 27Nov 30Dec 3Dec 8

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°F168161157153150146143139131
32°F188183178174169166162157151
28°F210204200196192188183178171
24°F236229224219215211207202194
20°F258252246241236232228222215
16°F275268263258254250246241233

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
6,956
Cooling degree days, base 65°F
690
Growing degree days, base 40°F
4,846
Growing degree days, base 45°F
3,767
Growing degree days, base 50°F
2,811
Growing degree days, base 55°F
1,977
Growing degree days, base 60°F
1,267

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40700
February1,15601
March920117
April534378
May22644303
June37156569
July6234693
August15180629
September13666386
October4597121
November837015
December1,22101

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 21 km from Davis. 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 USC00113262 (Freeport Waste Wtp). Public domain.