Lebanon climate

Lebanon Frost Dates and Growing Season

NOAA 1991-2020 normals for Lebanon 2W, 2.7 km from Lebanon, elevation 1246 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lebanon 2W. 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 April 17 and the first fall freeze around October 21, a growing season of about 187 days.

Median at 36°F
last April 29, first October 11
Median at 32°F
last April 17, first October 21
Median at 28°F
last April 4, first October 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°FMay 14May 9May 4May 1Apr 29Apr 25Apr 22Apr 18Apr 12
32°FMay 2Apr 28Apr 24Apr 20Apr 17Apr 13Apr 9Apr 5Mar 31
28°FApr 22Apr 17Apr 12Apr 8Apr 4Mar 31Mar 28Mar 24Mar 18
24°FApr 10Apr 3Mar 31Mar 28Mar 24Mar 21Mar 17Mar 13Mar 6
20°FMar 31Mar 24Mar 21Mar 16Mar 13Mar 9Mar 5Mar 1Feb 25
16°FMar 21Mar 15Mar 11Mar 7Mar 4Mar 1Feb 27Feb 22Feb 15

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°FSep 27Oct 2Oct 6Oct 9Oct 11Oct 14Oct 17Oct 20Oct 25
32°FOct 7Oct 12Oct 16Oct 19Oct 21Oct 24Oct 27Oct 30Nov 3
28°FOct 16Oct 21Oct 25Oct 28Oct 30Nov 2Nov 4Nov 8Nov 14
24°FOct 25Oct 31Nov 2Nov 5Nov 9Nov 12Nov 15Nov 21Nov 27
20°FNov 2Nov 7Nov 12Nov 15Nov 18Nov 23Nov 28Dec 3Dec 9
16°FNov 10Nov 17Nov 22Nov 26Dec 1Dec 5Dec 10Dec 15Dec 20

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°F186179174168164160155151144
32°F211203197192187182177171163
28°F232225220215210206201194185
24°F253245240234230226221215207
20°F276268261256251247241235227
16°F300289282276270265260254245

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
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% 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
4,618
Cooling degree days, base 65°F
1,316
Growing degree days, base 40°F
6,628
Growing degree days, base 45°F
5,284
Growing degree days, base 50°F
4,080
Growing degree days, base 55°F
3,019
Growing degree days, base 60°F
2,096

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,01209
February798018
March593484
April29719223
May100101470
June7257700
July0396860
August2354817
September50152553
October26930265
November592368
December897014

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 2.7 km from Lebanon. 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 USC00234825 (Lebanon 2W). Public domain.