Erma climate

Erma Frost Dates and Growing Season

NOAA 1991-2020 normals for Cape May 2 Nw, 4.9 km from Erma, elevation 20 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cape May 2 Nw. 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 1 and the first fall freeze around November 9, a growing season of about 222 days.

Median at 36°F
last April 17, first October 29
Median at 32°F
last April 1, first November 9
Median at 28°F
last March 19, first November 23

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 2Apr 27Apr 23Apr 19Apr 17Apr 14Apr 10Apr 7Apr 3
32°FApr 15Apr 10Apr 7Apr 4Apr 1Mar 30Mar 28Mar 24Mar 19
28°FMar 31Mar 29Mar 26Mar 23Mar 19Mar 17Mar 14Mar 10Mar 4
24°FMar 23Mar 18Mar 15Mar 12Mar 9Mar 5Mar 2Feb 26Feb 20
20°FMar 14Mar 9Mar 5Mar 1Feb 26Feb 21Feb 15Feb 10Feb 2
16°FMar 3Feb 26Feb 20Feb 13Feb 7Feb 3Jan 31Jan 25Jan 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°FOct 13Oct 19Oct 23Oct 27Oct 29Nov 1Nov 3Nov 6Nov 11
32°FOct 26Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 26
28°FNov 7Nov 12Nov 16Nov 20Nov 23Nov 27Nov 30Dec 4Dec 11
24°FNov 18Nov 24Nov 29Dec 3Dec 6Dec 10Dec 15Dec 19Dec 26
20°FDec 1Dec 8Dec 15Dec 19Dec 24Dec 28Jan 2Jan 8Jan 17
16°FDec 16Dec 24Jan 1Jan 4Jan 8Jan 12Jan 18Jan 25Feb 3

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°F213207202198193189185180172
32°F242236229225222218213208201
28°F272264257253248244238233226
24°F302293286280275270264258250
20°F329319312306302297291285275
16°F365347337333327321314306298

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
99% of years
16°F or colder
91% 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
4,332
Cooling degree days, base 65°F
1,176
Growing degree days, base 40°F
6,438
Growing degree days, base 45°F
5,047
Growing degree days, base 50°F
3,833
Growing degree days, base 55°F
2,789
Growing degree days, base 60°F
1,907

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January90205
February77605
March665028
April3676136
May13349382
June13210647
July0369834
August0334798
September22177605
October20731299
November488178
December758017

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 4.9 km from Erma. 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 USC00281351 (Cape May 2 Nw). Public domain.