Carlsbad climate

Carlsbad Frost Dates and Growing Season

NOAA 1991-2020 normals for Water Valley, 11 km from Carlsbad, elevation 2115 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Water Valley. 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 6 and the first fall freeze around November 2, a growing season of about 211 days.

Median at 36°F
last April 17, first October 25
Median at 32°F
last April 6, first November 2
Median at 28°F
last March 21, first November 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°FMay 2Apr 28Apr 24Apr 20Apr 17Apr 14Apr 11Apr 7Apr 2
32°FApr 24Apr 17Apr 13Apr 9Apr 6Apr 2Mar 29Mar 22Mar 14
28°FApr 12Apr 4Mar 31Mar 26Mar 21Mar 15Mar 11Mar 6Feb 28
24°FMar 27Mar 19Mar 13Mar 9Mar 5Mar 2Feb 26Feb 22Feb 14
20°FMar 13Mar 6Mar 1Feb 26Feb 20Feb 15Feb 9Feb 1Jan 21
16°FMar 3Feb 23Feb 13Feb 6Feb 1Jan 27Jan 20Jan 9Dec 27

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 8Oct 15Oct 19Oct 22Oct 25Oct 28Oct 31Nov 3Nov 6
32°FOct 18Oct 24Oct 28Nov 1Nov 2Nov 5Nov 7Nov 10Nov 16
28°FOct 28Nov 2Nov 5Nov 8Nov 11Nov 14Nov 17Nov 22Nov 28
24°FNov 4Nov 10Nov 14Nov 18Nov 22Nov 26Nov 30Dec 3Dec 10
20°FNov 15Nov 21Nov 26Nov 30Dec 3Dec 7Dec 13Dec 22Jan 2
16°FNov 26Dec 2Dec 7Dec 14Dec 22Dec 30Jan 5Jan 14Jan 30

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°F211204198192188184180174166
32°F236226220215211206200194187
28°F264254248242237231225218209
24°F290280274269263257251244233
20°F325312303296289282275269258
16°F365354343334328319310301289

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
99% of years
16°F or colder
89% 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
2,561
Cooling degree days, base 65°F
2,467
Growing degree days, base 40°F
9,183
Growing degree days, base 45°F
7,549
Growing degree days, base 50°F
6,049
Growing degree days, base 55°F
4,696
Growing degree days, base 60°F
3,501

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January625150
February457495
March28727254
April11498443
May22287730
June0477927
July05701,035
August05521,017
September11323762
October102115486
November35314185
December590164

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 km from Carlsbad. 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 USC00419499 (Water Valley). Public domain.