Hancock County climate

Hancock County Frost Dates and Growing Season

NOAA 1991-2020 normals for Bay St Louis Nasa, 12.1 km from Hancock County, elevation 30 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bay St Louis Nasa. 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 6 and the first fall freeze around November 19, a growing season of about 262 days.

Median at 36°F
last March 22, first November 7
Median at 32°F
last March 6, first November 19
Median at 28°F
last February 16, first December 4

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 11Apr 5Mar 31Mar 26Mar 22Mar 18Mar 12Mar 6Feb 27
32°FMar 27Mar 20Mar 16Mar 10Mar 6Mar 1Feb 24Feb 18Feb 5
28°FMar 16Mar 8Mar 1Feb 24Feb 16Feb 8Jan 31Jan 25Jan 12
24°FMar 5Feb 26Feb 12Feb 3Jan 30Jan 22Jan 13Jan 4Dec 25
20°FFeb 26Feb 9Feb 1Jan 28Jan 22Jan 12Jan 5Dec 29Dec 13
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°FOct 26Oct 31Nov 2Nov 4Nov 7Nov 10Nov 14Nov 19Nov 27
32°FNov 3Nov 6Nov 10Nov 15Nov 19Nov 24Nov 30Dec 4Dec 13
28°FNov 9Nov 18Nov 24Nov 30Dec 4Dec 10Dec 23Jan 3Jan 16
24°FNov 23Dec 2Dec 10Dec 21Dec 31Jan 5Jan 13Jan 25Feb 6
20°FDec 5Dec 17Dec 29Jan 2Jan 8Jan 16Jan 25Feb 1Feb 10
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°F264254246240235229223216206
32°F299285276269262254247240231
28°F337324312303296288280270256
24°F365365354342334325314303289
20°F365365365365365365353337322
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
98% of years
24°F or colder
81% of years
20°F or colder
37% of years
16°F or colder
6% 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
1,911
Cooling degree days, base 65°F
2,140
Growing degree days, base 40°F
9,395
Growing degree days, base 45°F
7,657
Growing degree days, base 50°F
6,027
Growing degree days, base 55°F
4,555
Growing degree days, base 60°F
3,255

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4773108
February3449141
March22826285
April9375434
May11222676
June0387837
July0468933
August0462927
September1328777
October63128532
November26124244
December4339134

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 12.1 km from Hancock County. 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 USC00220521 (Bay St Louis Nasa). Public domain.