Castroville climate

Castroville Frost Dates and Growing Season

NOAA 1991-2020 normals for Lytle 3W, 13.8 km from Castroville, elevation 722 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lytle 3W. 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 24 and the first fall freeze around December 2, a growing season of about 283 days.

Median at 36°F
last March 6, first November 21
Median at 32°F
last February 24, first December 2
Median at 28°F
last February 4, first December 18

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°FMar 27Mar 20Mar 14Mar 10Mar 6Mar 3Feb 28Feb 23Feb 15
32°FMar 14Mar 9Mar 4Feb 28Feb 24Feb 19Feb 12Feb 2Jan 23
28°FMar 7Feb 27Feb 20Feb 12Feb 4Jan 29Jan 20Jan 8Dec 26
24°FMar 1Feb 16Feb 7Feb 1Jan 21Jan 10Jan 2Dec 27Dec 14
20°FFeb 22Feb 7Feb 1Jan 18Jan 6Jan 2Dec 28Dec 22Dec 13
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°FNov 1Nov 6Nov 12Nov 16Nov 21Nov 25Nov 29Dec 4Dec 10
32°FNov 14Nov 21Nov 25Nov 30Dec 2Dec 6Dec 11Dec 19Dec 30
28°FNov 25Dec 1Dec 5Dec 10Dec 18Dec 24Jan 1Jan 8Jan 30
24°FDec 3Dec 9Dec 18Dec 24Dec 30Jan 4Jan 14Jan 30Feb 12
20°FDec 10Dec 19Dec 25Dec 30Jan 3Jan 8Jan 22Feb 3Feb 14
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°F285275268263257252246238227
32°F320306298291283277270264253
28°F357343334324316308301291278
24°F365365365362352343334322306
20°F365365365365365365365356337
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
92% of years
24°F or colder
61% of years
20°F or colder
27% of years
16°F or colder
3% 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
1,210
Cooling degree days, base 65°F
3,252
Growing degree days, base 40°F
11,181
Growing degree days, base 45°F
9,391
Growing degree days, base 50°F
7,659
Growing degree days, base 55°F
6,038
Growing degree days, base 60°F
4,561

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3478180
February23425236
March11190454
April25211637
May1367831
June0541991
July06111,076
August06081,072
September1454903
October24245687
November14576392
December32316202

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 13.8 km from Castroville. 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 USC00415454 (Lytle 3W). Public domain.