McElhattan climate

McElhattan Frost Dates and Growing Season

NOAA 1991-2020 normals for Lock Haven Sewage Plt, 6.9 km from McElhattan, elevation 566 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lock Haven Sewage Plt. 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 30 and the first fall freeze around October 20, a growing season of about 173 days.

Median at 36°F
last May 9, first October 7
Median at 32°F
last April 30, first October 20
Median at 28°F
last April 16, 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 26May 21May 17May 13May 9May 6May 2Apr 30Apr 25
32°FMay 15May 9May 6May 2Apr 30Apr 26Apr 23Apr 20Apr 16
28°FMay 1Apr 26Apr 21Apr 19Apr 16Apr 13Apr 10Apr 6Apr 1
24°FApr 16Apr 11Apr 7Apr 5Apr 3Apr 1Mar 29Mar 25Mar 20
20°FApr 4Mar 31Mar 29Mar 25Mar 21Mar 18Mar 15Mar 11Mar 6
16°FMar 26Mar 22Mar 18Mar 15Mar 13Mar 9Mar 6Mar 2Feb 26

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 25Sep 30Oct 2Oct 5Oct 7Oct 11Oct 14Oct 17Oct 21
32°FOct 5Oct 10Oct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1
28°FOct 17Oct 23Oct 27Oct 31Nov 1Nov 3Nov 5Nov 8Nov 13
24°FNov 1Nov 3Nov 6Nov 9Nov 12Nov 14Nov 17Nov 21Nov 26
20°FNov 8Nov 13Nov 17Nov 20Nov 24Nov 28Dec 1Dec 4Dec 9
16°FNov 18Nov 24Nov 29Dec 2Dec 5Dec 10Dec 14Dec 21Dec 27

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°F170163158154150146141136129
32°F192185181177173168164159150
28°F217210205201197193189184177
24°F242234229226222218214210203
20°F270262256251247243237231225
16°F294286279274269265260254247

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
6,068
Cooling degree days, base 65°F
730
Growing degree days, base 40°F
5,098
Growing degree days, base 45°F
3,955
Growing degree days, base 50°F
2,948
Growing degree days, base 55°F
2,073
Growing degree days, base 60°F
1,331

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,19001
February1,01901
March864015
April482597
May19944321
June36141555
July3251713
August8205662
September9975428
October4108135
November729018
December1,02903

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 6.9 km from McElhattan. 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 USC00365109 (Lock Haven Sewage Plt). Public domain.