McKean County climate

McKean County Frost Dates and Growing Season

NOAA 1991-2020 normals for Bradford Rgnl AP, 5.9 km from McKean County, elevation 2117 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bradford Rgnl AP. 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 October 1, a growing season of about 136 days.

Median at 36°F
last June 1, first September 19
Median at 32°F
last May 18, first October 1
Median at 28°F
last May 3, first October 14

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 18Jun 11Jun 8Jun 4Jun 1May 30May 27May 23May 17
32°FMay 31May 27May 24May 21May 18May 14May 10May 5Apr 30
28°FMay 21May 16May 10May 7May 3Apr 30Apr 27Apr 23Apr 18
24°FMay 8May 1Apr 28Apr 23Apr 20Apr 17Apr 13Apr 9Apr 3
20°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 3Apr 1Mar 28Mar 23
16°FApr 9Apr 4Apr 2Mar 31Mar 28Mar 25Mar 21Mar 17Mar 13

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°FAug 29Sep 5Sep 11Sep 15Sep 19Sep 22Sep 24Sep 28Oct 1
32°FSep 18Sep 23Sep 26Sep 29Oct 1Oct 3Oct 6Oct 10Oct 15
28°FSep 30Oct 4Oct 6Oct 11Oct 14Oct 18Oct 21Oct 26Nov 2
24°FOct 11Oct 18Oct 23Oct 27Oct 31Nov 2Nov 5Nov 10Nov 17
20°FOct 26Nov 2Nov 5Nov 9Nov 13Nov 16Nov 20Nov 25Dec 1
16°FNov 8Nov 13Nov 17Nov 20Nov 24Nov 28Dec 1Dec 5Dec 13

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°F129121116110106101978980
32°F158150145140136132128123115
28°F188181176169166161155149143
24°F214207202197191187181176167
20°F242234229224219215211206198
16°F262256250246241237232227221

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
7,224
Cooling degree days, base 65°F
282
Growing degree days, base 40°F
4,037
Growing degree days, base 45°F
2,978
Growing degree days, base 50°F
2,065
Growing degree days, base 55°F
1,300
Growing degree days, base 60°F
694

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29701
February1,12301
March992012
April606256
May31618211
June10955398
July43101522
August6077482
September20926279
October519386
November816015
December1,13303

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 5.9 km from McKean County. 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 USW00004751 (Bradford Rgnl AP). Public domain.