Emmitsburg climate

Emmitsburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Emmitsburg 2 Se, 4.9 km from Emmitsburg, elevation 403 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Emmitsburg 2 Se. 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 22 and the first fall freeze around October 20, a growing season of about 179 days.

Median at 36°F
last May 4, first October 10
Median at 32°F
last April 22, first October 20
Median at 28°F
last April 9, first October 31

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 22May 16May 11May 7May 4May 1Apr 29Apr 25Apr 20
32°FMay 9May 4Apr 30Apr 27Apr 22Apr 19Apr 16Apr 12Apr 7
28°FApr 25Apr 19Apr 16Apr 12Apr 9Apr 6Apr 3Apr 1Mar 28
24°FApr 13Apr 7Apr 4Apr 1Mar 30Mar 27Mar 23Mar 18Mar 12
20°FApr 1Mar 28Mar 24Mar 20Mar 16Mar 13Mar 9Mar 5Feb 28
16°FMar 23Mar 17Mar 13Mar 9Mar 6Mar 2Feb 28Feb 23Feb 16

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

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°F178170165161157154149144136
32°F200194188183179175170165158
28°F223216212207203199194189182
24°F251243238232227222217211204
20°F280271265259254249243238228
16°F305297291285280275269263253

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
5,239
Cooling degree days, base 65°F
914
Growing degree days, base 40°F
5,682
Growing degree days, base 45°F
4,429
Growing degree days, base 50°F
3,329
Growing degree days, base 55°F
2,380
Growing degree days, base 60°F
1,575

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,04904
February90004
March749126
April4048133
May16252360
June23177605
July1306770
August4252713
September71104484
October33415187
November633037
December91008

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 Emmitsburg. 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 USC00182906 (Emmitsburg 2 Se). Public domain.