Lyman climate

Lyman Frost Dates and Growing Season

NOAA 1991-2020 normals for Gulfport Naval Ctr, 13.1 km from Lyman, elevation 35 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Gulfport Naval Ctr. 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 18 and the first fall freeze around December 14, a growing season of about 300 days.

Median at 36°F
last March 5, first November 26
Median at 32°F
last February 18, first December 14
Median at 28°F
last January 31, first January 2

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 26Mar 19Mar 14Mar 10Mar 5Feb 28Feb 23Feb 18Feb 7
32°FMar 14Mar 6Feb 28Feb 24Feb 18Feb 11Feb 5Jan 30Jan 17
28°FMar 2Feb 23Feb 13Feb 5Jan 31Jan 25Jan 18Jan 10Dec 31
24°FFeb 25Feb 10Feb 2Jan 28Jan 22Jan 17Jan 11Jan 5Dec 30
20°FFeb 6Feb 1Jan 26Jan 19Jan 14Jan 10Jan 7Jan 2Dec 26
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 6Nov 12Nov 17Nov 22Nov 26Dec 1Dec 4Dec 10Dec 22
32°FNov 18Nov 27Dec 2Dec 8Dec 14Dec 23Dec 29Jan 4Jan 13
28°FDec 3Dec 14Dec 23Dec 29Jan 2Jan 6Jan 13Jan 21Feb 4
24°FDec 20Dec 29Jan 2Jan 6Jan 11Jan 15Jan 21Jan 30Feb 10
20°FDec 25Jan 1Jan 4Jan 8Jan 11Jan 15Jan 21Jan 31Feb 5
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°F298287279273267260255248238
32°F338325315307300293286275263
28°F365362351343335330322310298
24°F365365365365365362351339327
20°F365365365365365365365365357
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
99% of years
28°F or colder
84% of years
24°F or colder
46% of years
20°F or colder
14% of years
16°F or colder
1% 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
1,430
Cooling degree days, base 65°F
2,694
Growing degree days, base 40°F
10,403
Growing degree days, base 45°F
8,624
Growing degree days, base 50°F
6,918
Growing degree days, base 55°F
5,334
Growing degree days, base 60°F
3,921

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3973147
February2748185
March15540358
April45131536
May2314777
June0453903
July05471,012
August05411,006
September0414864
October36193623
November18540320
December33610188

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 13.1 km from Lyman. 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 USC00223671 (Gulfport Naval Ctr). Public domain.