Somerset climate

Somerset Frost Dates and Growing Season

NOAA 1991-2020 normals for Somerset 2 N, 3 km from Somerset, elevation 1020 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Somerset 2 N. 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 5 and the first fall freeze around October 30, a growing season of about 206 days.

Median at 36°F
last April 19, first October 20
Median at 32°F
last April 5, first October 30
Median at 28°F
last March 25, first November 9

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 7May 2Apr 28Apr 22Apr 19Apr 15Apr 12Apr 8Apr 2
32°FApr 25Apr 18Apr 12Apr 8Apr 5Apr 2Mar 30Mar 27Mar 21
28°FApr 12Apr 3Mar 31Mar 28Mar 25Mar 21Mar 18Mar 13Mar 6
24°FMar 31Mar 25Mar 21Mar 17Mar 13Mar 9Mar 5Feb 28Feb 22
20°FMar 21Mar 16Mar 10Mar 5Mar 1Feb 26Feb 20Feb 12Feb 2
16°FMar 13Mar 5Feb 28Feb 21Feb 14Feb 8Feb 4Jan 29Jan 17

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 6Oct 11Oct 14Oct 17Oct 20Oct 22Oct 25Oct 28Nov 1
32°FOct 17Oct 22Oct 25Oct 27Oct 30Nov 1Nov 4Nov 7Nov 13
28°FOct 28Nov 1Nov 3Nov 6Nov 9Nov 13Nov 16Nov 21Nov 29
24°FNov 5Nov 10Nov 15Nov 19Nov 23Nov 28Dec 1Dec 6Dec 13
20°FNov 16Nov 23Nov 29Dec 2Dec 6Dec 11Dec 19Dec 26Jan 3
16°FNov 30Dec 6Dec 12Dec 20Dec 26Dec 31Jan 3Jan 10Jan 21

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°F205197193188184179174169162
32°F229221215211206202198192184
28°F256247239234229224220214207
24°F283274266259254248243237228
20°F313303296290283276269261251
16°F339329322315308302296288275

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
98% 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
3,861
Cooling degree days, base 65°F
1,450
Growing degree days, base 40°F
7,201
Growing degree days, base 45°F
5,750
Growing degree days, base 50°F
4,444
Growing degree days, base 55°F
3,292
Growing degree days, base 60°F
2,296

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January862022
February682133
March5166110
April22442298
May76127517
June6283727
July0395860
August1359823
September30190611
October21541313
November502496
December747034

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 3 km from Somerset. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00157510 (Somerset 2 N). Public domain.