Brownsville climate

Brownsville Frost Dates and Growing Season

NOAA 1991-2020 normals for Brownsville, 0.6 km from Brownsville, elevation 330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brownsville. 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 March 29 and the first fall freeze around November 5, a growing season of about 221 days.

Median at 36°F
last April 9, first October 27
Median at 32°F
last March 29, first November 5
Median at 28°F
last March 16, first November 17

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 25Apr 19Apr 15Apr 11Apr 9Apr 6Apr 2Mar 30Mar 23
32°FApr 15Apr 9Apr 4Apr 1Mar 29Mar 25Mar 21Mar 16Mar 9
28°FApr 5Mar 31Mar 24Mar 20Mar 16Mar 12Mar 7Mar 2Feb 25
24°FMar 23Mar 17Mar 11Mar 6Mar 2Feb 27Feb 23Feb 17Feb 8
20°FMar 11Mar 3Feb 28Feb 22Feb 15Feb 10Feb 5Jan 31Jan 22
16°FMar 2Feb 21Feb 13Feb 6Feb 1Jan 28Jan 22Jan 15Jan 5

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 14Oct 19Oct 23Oct 25Oct 27Oct 30Nov 1Nov 4Nov 9
32°FOct 24Oct 30Nov 1Nov 3Nov 5Nov 8Nov 11Nov 16Nov 22
28°FNov 3Nov 7Nov 11Nov 14Nov 17Nov 22Nov 26Dec 1Dec 6
24°FNov 10Nov 16Nov 21Nov 25Nov 30Dec 3Dec 8Dec 15Dec 22
20°FNov 21Nov 29Dec 4Dec 12Dec 19Dec 24Dec 29Jan 3Jan 14
16°FDec 5Dec 18Dec 24Dec 29Jan 1Jan 7Jan 13Jan 20Feb 1

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°F221215210206201197193188181
32°F246237230225221217212208201
28°F273264257252246241235229221
24°F303293285278272266261254244
20°F334324316308301294287280269
16°F365354344336331325316306296

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
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
3,399
Cooling degree days, base 65°F
1,955
Growing degree days, base 40°F
8,046
Growing degree days, base 45°F
6,544
Growing degree days, base 50°F
5,179
Growing degree days, base 55°F
3,958
Growing degree days, base 60°F
2,883

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January806127
February614148
March43312154
April17959350
May36197626
June1387835
July0496961
August0460925
September15267702
October16468382
November4447128
December706140

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 0.6 km from Brownsville. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00401145 (Brownsville). Public domain.