Lancaster County climate

Lancaster County Frost Dates and Growing Season

NOAA 1991-2020 normals for Lincoln Muni AP, 9 km from Lancaster County, elevation 1190 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lincoln 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 April 24 and the first fall freeze around October 13, a growing season of about 171 days.

Median at 36°F
last May 2, first October 4
Median at 32°F
last April 24, first October 13
Median at 28°F
last April 15, first October 22

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 16May 13May 8May 5May 2Apr 30Apr 28Apr 25Apr 20
32°FMay 7May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 10
28°FApr 29Apr 25Apr 21Apr 17Apr 15Apr 11Apr 9Apr 5Apr 2
24°FApr 20Apr 15Apr 11Apr 7Apr 5Apr 2Mar 31Mar 26Mar 19
20°FApr 11Apr 5Apr 2Mar 30Mar 27Mar 23Mar 19Mar 14Mar 9
16°FApr 2Mar 28Mar 23Mar 19Mar 15Mar 12Mar 8Mar 4Feb 27

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 21Sep 26Sep 29Oct 2Oct 4Oct 6Oct 9Oct 13Oct 16
32°FSep 29Oct 3Oct 7Oct 10Oct 13Oct 16Oct 18Oct 21Oct 24
28°FOct 8Oct 14Oct 17Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2
24°FOct 17Oct 22Oct 25Oct 28Oct 31Nov 2Nov 4Nov 8Nov 13
20°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 19Nov 25
16°FNov 1Nov 7Nov 11Nov 14Nov 18Nov 22Nov 26Nov 29Dec 4

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°F171165160157153150146141134
32°F189184179175171167163158151
28°F207201196193189185181176169
24°F228220215211208203199194186
20°F250243236232226222218212204
16°F269262256251246241236231222

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
5,856
Cooling degree days, base 65°F
1,270
Growing degree days, base 40°F
5,983
Growing degree days, base 45°F
4,791
Growing degree days, base 50°F
3,726
Growing degree days, base 55°F
2,785
Growing degree days, base 60°F
1,964

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24000
February99404
March741245
April40111151
May14384412
June12271709
July1405869
August3333795
September77143518
October36720193
November755128
December1,12201

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 9 km from Lancaster County. 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 USW00014939 (Lincoln Muni AP). Public domain.