Plaquemines Parish climate

Plaquemines Parish Frost Dates and Growing Season

NOAA 1991-2020 normals for Lsu Citrus Rsch Stn, 4.2 km from Plaquemines Parish, elevation 4 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lsu Citrus Rsch Stn. 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 3 and the first fall freeze around December 28, a growing season of about 327 days.

Median at 36°F
last February 22, first December 12
Median at 32°F
last February 3, first December 28
Median at 28°F
last January 23, first January 7

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 15Mar 8Mar 3Feb 27Feb 22Feb 17Feb 11Feb 6Jan 26
32°FMar 2Feb 21Feb 14Feb 8Feb 3Jan 30Jan 23Jan 15Jan 2
28°FFeb 14Feb 6Jan 31Jan 27Jan 23Jan 16Jan 10Jan 3Dec 27
24°FFeb 7Jan 31Jan 27Jan 21Jan 16Jan 12Jan 8Jan 2Dec 26
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 24Dec 1Dec 5Dec 8Dec 12Dec 17Dec 23Dec 30Jan 8
32°FDec 5Dec 11Dec 17Dec 23Dec 28Jan 2Jan 9Jan 17Jan 31
28°FDec 14Dec 24Dec 31Jan 3Jan 7Jan 13Jan 19Jan 28Feb 6
24°FDec 25Jan 1Jan 5Jan 8Jan 12Jan 15Jan 21Jan 29Feb 5
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°F328316307302295290284276267
32°F365351340333327320311306292
28°F365365365365363354343335324
24°F365365365365365365365365349
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
19% of years
20°F or colder
3% 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
1,140
Cooling degree days, base 65°F
2,948
Growing degree days, base 40°F
10,945
Growing degree days, base 45°F
9,153
Growing degree days, base 50°F
7,407
Growing degree days, base 55°F
5,760
Growing degree days, base 60°F
4,270

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January33616203
February23317221
March11960412
April34148565
May2340803
June0483933
July05431,007
August05521,017
September0451901
October19241687
November12468401
December27431258

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 4.2 km from Plaquemines Parish. 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 USC00165624 (Lsu Citrus Rsch Stn). Public domain.