Slidell climate

Slidell Frost Dates and Growing Season

NOAA 1991-2020 normals for Slidell, 1.6 km from Slidell, elevation 10 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Slidell. 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 24 and the first fall freeze around December 1, a growing season of about 281 days.

Median at 36°F
last March 12, first November 16
Median at 32°F
last February 24, first December 1
Median at 28°F
last February 4, first December 26

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 2Mar 27Mar 22Mar 17Mar 12Mar 6Mar 1Feb 24Feb 18
32°FMar 19Mar 12Mar 5Feb 28Feb 24Feb 20Feb 14Feb 6Jan 29
28°FMar 6Feb 25Feb 18Feb 11Feb 4Jan 31Jan 23Jan 14Jan 4
24°FFeb 23Feb 11Feb 2Jan 29Jan 22Jan 15Jan 9Jan 3Dec 26
20°FFeb 8Feb 2Jan 29Jan 23Jan 16Jan 11Jan 6Jan 1Dec 25
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 1Nov 5Nov 9Nov 13Nov 16Nov 20Nov 24Dec 1Dec 7
32°FNov 9Nov 15Nov 20Nov 26Dec 1Dec 5Dec 12Dec 25Jan 3
28°FNov 26Dec 2Dec 8Dec 16Dec 26Jan 1Jan 5Jan 12Jan 26
24°FDec 8Dec 22Dec 29Jan 2Jan 5Jan 10Jan 16Jan 27Feb 4
20°FDec 21Dec 29Jan 1Jan 5Jan 8Jan 15Jan 22Jan 29Feb 3
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°F279270262256250245240232222
32°F319307297288281275268260251
28°F361344334328321313306297282
24°F365365365361351344336328314
20°F365365365365365365365356341
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
100% of years
28°F or colder
94% of years
24°F or colder
65% of years
20°F or colder
25% of years
16°F or colder
5% 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
1,599
Cooling degree days, base 65°F
2,590
Growing degree days, base 40°F
10,147
Growing degree days, base 45°F
8,390
Growing degree days, base 50°F
6,722
Growing degree days, base 55°F
5,184
Growing degree days, base 60°F
3,799

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4387136
February30213178
March17647350
April57114508
May5295755
June0454904
July0518983
August0515980
September1397846
October45177598
November20539304
December37015181

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 1.6 km from Slidell. 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 USC00168539 (Slidell). Public domain.