Shippensburg climate

Shippensburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Shippensburg, 0.9 km from Shippensburg, elevation 680 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Shippensburg. 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 19 and the first fall freeze around October 24, a growing season of about 188 days.

Median at 36°F
last April 30, first October 11
Median at 32°F
last April 19, first October 24
Median at 28°F
last April 5, first November 4

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 18May 11May 7May 3Apr 30Apr 28Apr 24Apr 21Apr 16
32°FMay 6Apr 30Apr 25Apr 22Apr 19Apr 16Apr 12Apr 8Apr 4
28°FApr 17Apr 14Apr 10Apr 7Apr 5Apr 2Mar 31Mar 28Mar 22
24°FApr 6Apr 2Mar 31Mar 28Mar 25Mar 22Mar 18Mar 14Mar 9
20°FMar 27Mar 23Mar 19Mar 16Mar 13Mar 10Mar 7Mar 3Feb 26
16°FMar 19Mar 14Mar 10Mar 7Mar 4Mar 1Feb 26Feb 21Feb 13

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 28Oct 2Oct 5Oct 8Oct 11Oct 14Oct 17Oct 21Oct 26
32°FOct 9Oct 13Oct 17Oct 21Oct 24Oct 27Oct 30Nov 1Nov 6
28°FOct 21Oct 26Oct 30Nov 1Nov 4Nov 6Nov 9Nov 13Nov 19
24°FNov 2Nov 6Nov 9Nov 13Nov 16Nov 20Nov 24Nov 28Dec 4
20°FNov 11Nov 17Nov 21Nov 26Nov 30Dec 3Dec 7Dec 14Dec 21
16°FNov 26Dec 3Dec 8Dec 13Dec 18Dec 22Dec 26Dec 31Jan 7

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°F183176171167163160156151142
32°F207200196191188184180174166
28°F232226221217212209205200194
24°F260251246241237233228224217
20°F286278271267262258252246238
16°F312304298292287282276270261

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
5,267
Cooling degree days, base 65°F
1,014
Growing degree days, base 40°F
5,809
Growing degree days, base 45°F
4,566
Growing degree days, base 50°F
3,462
Growing degree days, base 55°F
2,502
Growing degree days, base 60°F
1,686

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07903
February89904
March743131
April38712150
May14667390
June20207638
July1332797
August4274735
September71107487
October33114187
November639036
December94705

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 0.9 km from Shippensburg. 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 USC00368073 (Shippensburg). Public domain.