Guildhall climate

Guildhall Frost Dates and Growing Season

NOAA 1991-2020 normals for Lancaster, 7.8 km from Guildhall, elevation 860 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lancaster. 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 18 and the first fall freeze around September 30, a growing season of about 132 days.

Median at 36°F
last May 31, first September 18
Median at 32°F
last May 18, first September 30
Median at 28°F
last May 5, first October 9

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

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 5Sep 10Sep 13Sep 16Sep 18Sep 21Sep 24Sep 27Oct 1
32°FSep 16Sep 21Sep 25Sep 28Sep 30Oct 1Oct 3Oct 7Oct 12
28°FSep 27Oct 1Oct 3Oct 6Oct 9Oct 12Oct 16Oct 21Oct 27
24°FOct 7Oct 13Oct 17Oct 20Oct 24Oct 27Nov 1Nov 3Nov 8
20°FOct 19Oct 25Oct 30Nov 1Nov 3Nov 6Nov 9Nov 13Nov 18
16°FNov 1Nov 6Nov 10Nov 12Nov 15Nov 18Nov 21Nov 24Nov 28

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°F1281221181141111071049993
32°F151144139136132129124120114
28°F178171165161157154150144138
24°F205197192188184180176170163
20°F225219215211207204200195188
16°F242236231228225222218214208

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
8,619
Cooling degree days, base 65°F
249
Growing degree days, base 40°F
3,584
Growing degree days, base 45°F
2,651
Growing degree days, base 50°F
1,840
Growing degree days, base 55°F
1,154
Growing degree days, base 60°F
613

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57000
February1,36600
March1,20602
April745121
May3857147
June13146367
July41101525
August6472473
September24122251
October605150
November93305
December1,33100

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 7.8 km from Guildhall. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00274556 (Lancaster). Public domain.