Brownsville climate

Brownsville Frost Dates and Growing Season

NOAA 1991-2020 normals for Nolin Rvr Lake, 10 km from Brownsville, elevation 623 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Nolin Rvr Lake. 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 22 and the first fall freeze around October 22, a growing season of about 182 days.

Median at 36°F
last May 2, first October 12
Median at 32°F
last April 22, first October 22
Median at 28°F
last April 8, first November 1

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 19May 13May 9May 5May 2Apr 30Apr 26Apr 21Apr 16
32°FMay 11May 4Apr 30Apr 26Apr 22Apr 18Apr 15Apr 11Apr 5
28°FApr 27Apr 21Apr 16Apr 11Apr 8Apr 4Apr 1Mar 29Mar 23
24°FApr 14Apr 7Apr 3Mar 31Mar 28Mar 24Mar 20Mar 15Mar 6
20°FApr 2Mar 28Mar 23Mar 19Mar 15Mar 11Mar 5Feb 28Feb 21
16°FMar 21Mar 15Mar 10Mar 4Feb 28Feb 24Feb 19Feb 13Feb 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°FSep 30Oct 4Oct 7Oct 10Oct 12Oct 15Oct 18Oct 22Oct 25
32°FOct 9Oct 14Oct 16Oct 19Oct 22Oct 25Oct 27Oct 31Nov 3
28°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 15
24°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 23Nov 30
20°FNov 6Nov 11Nov 15Nov 20Nov 24Nov 28Dec 1Dec 6Dec 14
16°FNov 15Nov 22Nov 28Dec 1Dec 6Dec 11Dec 17Dec 22Dec 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°F181175170165161157153148142
32°F203197191186182176172167160
28°F229220214210205201195190181
24°F256247241235230225220214208
20°F284275268261255249243236227
16°F312302295287282275269262253

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
4,278
Cooling degree days, base 65°F
1,412
Growing degree days, base 40°F
6,893
Growing degree days, base 45°F
5,502
Growing degree days, base 50°F
4,260
Growing degree days, base 55°F
3,166
Growing degree days, base 60°F
2,219

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January930017
February751021
March584685
April28628241
May93116491
June9280721
July0392857
August1361825
September36187602
October23838291
November537383
December814025

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 10 km from Brownsville. 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 USC00155834 (Nolin Rvr Lake). Public domain.