Epsom climate

Epsom Frost Dates and Growing Season

NOAA 1991-2020 normals for Concord Muni AP, 14 km from Epsom, elevation 346 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Concord Muni AP. 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 8 and the first fall freeze around October 3, a growing season of about 146 days.

Median at 36°F
last May 20, first September 23
Median at 32°F
last May 8, first October 3
Median at 28°F
last April 27, first October 13

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 3May 30May 27May 23May 20May 18May 15May 11May 7
32°FMay 22May 18May 15May 12May 8May 5May 3Apr 30Apr 27
28°FMay 9May 4May 2Apr 29Apr 27Apr 25Apr 22Apr 20Apr 15
24°FApr 25Apr 21Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Apr 2
20°FApr 14Apr 9Apr 6Apr 3Apr 2Mar 31Mar 29Mar 25Mar 19
16°FApr 5Apr 1Mar 30Mar 27Mar 24Mar 20Mar 17Mar 14Mar 9

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 9Sep 14Sep 17Sep 21Sep 23Sep 26Sep 29Oct 1Oct 5
32°FSep 21Sep 26Sep 29Oct 1Oct 3Oct 5Oct 7Oct 11Oct 16
28°FOct 1Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20Oct 23Oct 30
24°FOct 10Oct 15Oct 18Oct 22Oct 25Oct 28Nov 1Nov 4Nov 9
20°FOct 23Oct 29Nov 1Nov 4Nov 6Nov 10Nov 13Nov 17Nov 23
16°FNov 4Nov 9Nov 13Nov 17Nov 21Nov 24Nov 28Dec 1Dec 6

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°F143136131127124121117113106
32°F163158153149146142138134128
28°F188182177173169164161156151
24°F214207202198194191186181174
20°F239233227223219214211206199
16°F263255249245241237232227219

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
6,980
Cooling degree days, base 65°F
528
Growing degree days, base 40°F
4,452
Growing degree days, base 45°F
3,392
Growing degree days, base 50°F
2,472
Growing degree days, base 55°F
1,682
Growing degree days, base 60°F
1,029

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,32501
February1,12700
March97806
April590252
May27820229
June7194473
July10200654
August21159603
September16050347
October488392
November794014
December1,13801

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 14 km from Epsom. 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 USW00014745 (Concord Muni AP). Public domain.