Rio Bravo climate

Rio Bravo Frost Dates and Growing Season

NOAA 1991-2020 normals for Laredo 2, 22.8 km from Rio Bravo, elevation 430 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Laredo 2. 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 January 25 and the first fall freeze around December 17, a growing season of about 329 days.

Median at 36°F
last February 13, first December 3
Median at 32°F
last January 25, first December 17
Median at 28°F
last January 8, first December 30

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 9Mar 3Feb 25Feb 19Feb 13Feb 7Feb 3Jan 28Jan 18
32°FFeb 25Feb 13Feb 5Feb 1Jan 25Jan 20Jan 12Jan 4Dec 25
28°FFeb 11Feb 2Jan 23Jan 14Jan 8Jan 4Dec 31Dec 24Dec 14
24°FFeb 5Jan 22Jan 10Jan 5Jan 2Dec 30Dec 26Dec 17Dec 9
20°F–––––––––
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 14Nov 20Nov 24Nov 29Dec 3Dec 7Dec 12Dec 19Dec 28
32°FNov 23Dec 1Dec 6Dec 11Dec 17Dec 23Dec 30Jan 6Jan 19
28°FDec 5Dec 10Dec 16Dec 24Dec 30Jan 2Jan 8Jan 17Feb 1
24°FDec 7Dec 15Dec 22Dec 27Jan 1Jan 3Jan 7Jan 12Feb 1
20°F–––––––––
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°F328316307300293286279270260
32°F362351342335329321314304288
28°F365365365365363356348338325
24°F365365365365365365365365353
20°F365365365365365365365365365
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
90% of years
28°F or colder
55% of years
24°F or colder
21% of years
20°F or colder
4% of years
16°F or colder
0% 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
819
Cooling degree days, base 65°F
4,471
Growing degree days, base 40°F
12,783
Growing degree days, base 45°F
10,975
Growing degree days, base 50°F
9,202
Growing degree days, base 55°F
7,504
Growing degree days, base 60°F
5,920

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January26132267
February13977370
March56197609
April8357800
May05521,017
June06781,128
July07351,200
August07471,212
September15591,008
October12367820
November98130487
December24441285

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 22.8 km from Rio Bravo. 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 USC00415060 (Laredo 2). Public domain.