Somerset County climate

Somerset County Frost Dates and Growing Season

NOAA 1991-2020 normals for Brassua Dam, 19.9 km from Somerset County, elevation 1069 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brassua Dam. 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 May 23 and the first fall freeze around September 29, a growing season of about 128 days.

Median at 36°F
last June 3, first September 18
Median at 32°F
last May 23, first September 29
Median at 28°F
last May 9, first October 10

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°FJun 14Jun 10Jun 7Jun 5Jun 3Jun 1May 30May 27May 23
32°FJun 4Jun 1May 28May 25May 23May 20May 17May 14May 7
28°FMay 24May 19May 15May 12May 9May 6May 4May 1Apr 28
24°FMay 10May 6May 2Apr 30Apr 28Apr 25Apr 23Apr 20Apr 16
20°FApr 29Apr 25Apr 22Apr 19Apr 17Apr 15Apr 12Apr 9Apr 5
16°FApr 21Apr 16Apr 13Apr 10Apr 8Apr 6Apr 5Apr 3Mar 31

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 3Sep 9Sep 12Sep 15Sep 18Sep 20Sep 23Sep 27Oct 1
32°FSep 16Sep 22Sep 24Sep 27Sep 29Oct 1Oct 4Oct 6Oct 11
28°FSep 27Oct 1Oct 4Oct 7Oct 10Oct 13Oct 17Oct 20Oct 27
24°FOct 8Oct 14Oct 17Oct 21Oct 25Oct 28Nov 1Nov 3Nov 8
20°FOct 24Oct 30Nov 1Nov 3Nov 6Nov 10Nov 13Nov 16Nov 21
16°FNov 3Nov 8Nov 12Nov 14Nov 17Nov 19Nov 22Nov 25Nov 28

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°F122116112109106102999588
32°F146140136132128124120115111
28°F173166162158153149146141132
24°F197191187183178175170165157
20°F220215210206203199195191185
16°F238232228225221218214210203

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
9,378
Cooling degree days, base 65°F
164
Growing degree days, base 40°F
3,166
Growing degree days, base 45°F
2,296
Growing degree days, base 50°F
1,549
Growing degree days, base 55°F
929
Growing degree days, base 60°F
459

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65400
February1,46000
March1,30700
April86005
May474396
June18227302
July6269471
August8450431
September27814211
October654031
November97802
December1,38400

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 19.9 km from Somerset 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 USC00170814 (Brassua Dam). Public domain.