Saint Bernard Parish climate

Saint Bernard Parish Frost Dates and Growing Season

NOAA 1991-2020 normals for St Bernard, 0.6 km from Saint Bernard Parish, elevation 5 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for St Bernard. 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 4 and the first fall freeze around December 15, a growing season of about 312 days.

Median at 36°F
last February 26, first November 30
Median at 32°F
last February 4, first December 15
Median at 28°F
last January 21, 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 20Mar 12Mar 6Mar 1Feb 26Feb 20Feb 15Feb 7Jan 31
32°FMar 6Feb 27Feb 18Feb 11Feb 4Jan 31Jan 25Jan 16Dec 31
28°FFeb 23Feb 7Jan 31Jan 27Jan 21Jan 15Jan 8Dec 31Dec 21
24°FFeb 5Jan 30Jan 24Jan 18Jan 13Jan 9Jan 4Dec 31Dec 22
20°FFeb 1Jan 27Jan 22Jan 17Jan 14Jan 10Jan 7Jan 2Dec 30
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 12Nov 17Nov 22Nov 26Nov 30Dec 2Dec 5Dec 11Dec 23
32°FNov 23Dec 1Dec 5Dec 9Dec 15Dec 20Dec 26Jan 2Jan 10
28°FDec 4Dec 11Dec 18Dec 24Dec 30Jan 2Jan 7Jan 12Jan 24
24°FDec 18Dec 25Dec 31Jan 1Jan 5Jan 8Jan 12Jan 18Jan 27
20°FDec 27Jan 1Jan 2Jan 6Jan 11Jan 13Jan 18Jan 22Jan 28
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°F309299290284277271265257247
32°F348335328320312305297289275
28°F365365361351344338332323308
24°F365365365365365365357346336
20°F365365365365365365365365360
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
97% of years
28°F or colder
75% of years
24°F or colder
41% of years
20°F or colder
14% of years
16°F or colder
3% 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
1,374
Cooling degree days, base 65°F
2,710
Growing degree days, base 40°F
10,475
Growing degree days, base 45°F
8,693
Growing degree days, base 50°F
6,979
Growing degree days, base 55°F
5,387
Growing degree days, base 60°F
3,956

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3888156
February25917207
March14252383
April37138551
May2330794
June0454904
July0521986
August0522987
September0411861
October30197633
November17648333
December34011185

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 Saint Bernard Parish. 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 USC00168108 (St Bernard). Public domain.