Tinicum climate

Tinicum Frost Dates and Growing Season

NOAA 1991-2020 normals for Bucksville, 10 km from Tinicum, elevation 387 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bucksville. 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 29 and the first fall freeze around October 16, a growing season of about 170 days.

Median at 36°F
last May 10, first October 6
Median at 32°F
last April 29, first October 16
Median at 28°F
last April 17, first October 28

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 25May 20May 17May 13May 10May 7May 3Apr 30Apr 26
32°FMay 15May 9May 5May 2Apr 29Apr 27Apr 24Apr 20Apr 16
28°FMay 2Apr 26Apr 23Apr 20Apr 17Apr 14Apr 11Apr 7Apr 2
24°FApr 17Apr 12Apr 8Apr 5Apr 3Mar 31Mar 30Mar 26Mar 21
20°FApr 3Mar 31Mar 29Mar 26Mar 24Mar 20Mar 16Mar 12Mar 7
16°FMar 25Mar 21Mar 17Mar 14Mar 11Mar 8Mar 6Mar 1Feb 24

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 26Sep 30Oct 2Oct 4Oct 6Oct 9Oct 11Oct 15Oct 19
32°FOct 4Oct 7Oct 11Oct 14Oct 16Oct 19Oct 22Oct 26Nov 1
28°FOct 12Oct 17Oct 21Oct 24Oct 28Oct 31Nov 2Nov 4Nov 8
24°FOct 23Oct 29Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 20
20°FNov 5Nov 10Nov 12Nov 15Nov 18Nov 21Nov 25Nov 30Dec 6
16°FNov 13Nov 19Nov 23Nov 28Dec 1Dec 4Dec 8Dec 14Dec 21

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°F168161157153149145141136129
32°F190183178174170166161156150
28°F212206201197193188185180172
24°F236230225221217213209204198
20°F264256251246242237233228221
16°F289281274269264259254249242

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
5,653
Cooling degree days, base 65°F
810
Growing degree days, base 40°F
5,360
Growing degree days, base 45°F
4,159
Growing degree days, base 50°F
3,107
Growing degree days, base 55°F
2,194
Growing degree days, base 60°F
1,427

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11702
February95601
March811017
April4438118
May18646333
June35161576
July3280742
August8220677
September9084446
October37410159
November671030
December95905

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 10 km from Tinicum. 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 USC00361080 (Bucksville). Public domain.