Lancaster climate

Lancaster Frost Dates and Growing Season

NOAA 1991-2020 normals for Lancaster 4 Wsw, 6.7 km from Lancaster, elevation 1040 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lancaster 4 Wsw. 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 27 and the first fall freeze around October 11, a growing season of about 166 days.

Median at 36°F
last May 6, first October 2
Median at 32°F
last April 27, first October 11
Median at 28°F
last April 16, 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 20May 15May 12May 9May 6May 4May 2Apr 29Apr 23
32°FMay 11May 6May 3Apr 30Apr 27Apr 24Apr 21Apr 16Apr 11
28°FMay 1Apr 26Apr 22Apr 19Apr 16Apr 12Apr 10Apr 7Apr 3
24°FApr 21Apr 16Apr 12Apr 9Apr 7Apr 4Apr 2Mar 30Mar 23
20°FApr 12Apr 7Apr 3Mar 31Mar 29Mar 25Mar 22Mar 17Mar 12
16°FApr 3Mar 30Mar 26Mar 22Mar 19Mar 16Mar 12Mar 9Mar 4

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 19Sep 24Sep 27Sep 30Oct 2Oct 4Oct 7Oct 10Oct 15
32°FSep 27Oct 1Oct 5Oct 8Oct 11Oct 14Oct 17Oct 20Oct 24
28°FOct 6Oct 12Oct 17Oct 20Oct 22Oct 25Oct 27Oct 31Nov 3
24°FOct 19Oct 25Oct 28Oct 30Nov 1Nov 3Nov 6Nov 11Nov 16
20°FOct 31Nov 2Nov 6Nov 9Nov 11Nov 14Nov 17Nov 21Nov 27
16°FNov 6Nov 10Nov 14Nov 17Nov 20Nov 23Nov 26Nov 30Dec 5

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°F165159154151147143140136128
32°F187178174170166162158152146
28°F209203197193189184180175167
24°F229222217213209205201196190
20°F250243238233228224220215209
16°F267261254249245241237232224

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
7,365
Cooling degree days, base 65°F
599
Growing degree days, base 40°F
4,640
Growing degree days, base 45°F
3,586
Growing degree days, base 50°F
2,650
Growing degree days, base 55°F
1,836
Growing degree days, base 60°F
1,147

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48500
February1,22100
March967116
April554273
May24834275
June46130534
July11208662
August22160603
September15158366
October4946108
November881013
December1,28601

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 6.7 km from Lancaster. 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 USC00474546 (Lancaster 4 Wsw). Public domain.