Drexel climate

Drexel Frost Dates and Growing Season

NOAA 1991-2020 normals for Butler 4W, 30.1 km from Drexel, elevation 790 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Butler 4W. 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 12 and the first fall freeze around October 23, a growing season of about 192 days.

Median at 36°F
last April 23, first October 13
Median at 32°F
last April 12, first October 23
Median at 28°F
last April 2, first November 1

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 6May 2Apr 30Apr 26Apr 23Apr 20Apr 17Apr 13Apr 8
32°FApr 28Apr 22Apr 18Apr 15Apr 12Apr 8Apr 5Mar 31Mar 28
28°FApr 17Apr 12Apr 8Apr 5Apr 2Mar 30Mar 26Mar 21Mar 15
24°FApr 7Apr 2Mar 31Mar 26Mar 22Mar 18Mar 14Mar 9Mar 4
20°FMar 31Mar 24Mar 19Mar 15Mar 11Mar 8Mar 4Feb 28Feb 23
16°FMar 19Mar 14Mar 9Mar 6Mar 3Feb 28Feb 25Feb 19Feb 12

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 3Oct 6Oct 11Oct 13Oct 16Oct 20Oct 22Oct 26
32°FOct 9Oct 14Oct 17Oct 20Oct 23Oct 26Oct 28Oct 31Nov 4
28°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 5Nov 9Nov 14
24°FOct 27Nov 1Nov 3Nov 6Nov 10Nov 14Nov 19Nov 24Nov 29
20°FNov 3Nov 8Nov 13Nov 17Nov 22Nov 26Dec 1Dec 4Dec 10
16°FNov 12Nov 19Nov 25Nov 30Dec 2Dec 7Dec 12Dec 16Dec 22

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°F192185180176172168164159151
32°F213206201196192189184179173
28°F234226220216212207203196190
24°F260250244238233228223218209
20°F281271265259254248242237228
16°F300291285280276270265258247

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
4,874
Cooling degree days, base 65°F
1,469
Growing degree days, base 40°F
6,667
Growing degree days, base 45°F
5,361
Growing degree days, base 50°F
4,191
Growing degree days, base 55°F
3,152
Growing degree days, base 60°F
2,244

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,08604
February851013
March630370
April32819204
May100110479
June6300744
July0443908
August1386849
September48171574
October26835272
November612264
December944011

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 30.1 km from Drexel. 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 USC00231145 (Butler 4W). Public domain.