Morgan County climate

Morgan County Frost Dates and Growing Season

NOAA 1991-2020 normals for Morgan, 10.4 km from Morgan County, elevation 5100 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Morgan. 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 25 and the first fall freeze around September 24, a growing season of about 119 days.

Median at 36°F
last June 11, first September 14
Median at 32°F
last May 25, first September 24
Median at 28°F
last May 8, first October 4

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 26Jun 20Jun 17Jun 13Jun 11Jun 8Jun 5Jun 2May 28
32°FJun 13Jun 7Jun 3May 30May 25May 21May 16May 11May 7
28°FMay 31May 22May 16May 11May 8May 5May 1Apr 28Apr 22
24°FMay 9May 2Apr 29Apr 25Apr 21Apr 18Apr 14Apr 9Apr 4
20°FApr 23Apr 17Apr 11Apr 7Apr 4Apr 1Mar 29Mar 22Mar 16
16°FApr 8Apr 3Mar 30Mar 25Mar 20Mar 16Mar 11Mar 7Mar 2

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 1Sep 5Sep 9Sep 12Sep 14Sep 17Sep 20Sep 23Sep 28
32°FSep 11Sep 15Sep 18Sep 21Sep 24Sep 27Sep 30Oct 2Oct 6
28°FSep 21Sep 26Sep 28Oct 1Oct 4Oct 6Oct 9Oct 14Oct 19
24°FOct 1Oct 5Oct 9Oct 13Oct 17Oct 19Oct 23Oct 26Nov 1
20°FOct 13Oct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 7Nov 14
16°FOct 22Oct 29Nov 1Nov 4Nov 8Nov 10Nov 14Nov 18Nov 24

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°F112106100979390858072
32°F14213412912311911511010497
28°F168161156152147143138130121
24°F199191185180176172167162153
20°F229221214209205200195189180
16°F257247240235230225220215206

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
6,847
Cooling degree days, base 65°F
487
Growing degree days, base 40°F
4,330
Growing degree days, base 45°F
3,251
Growing degree days, base 50°F
2,331
Growing degree days, base 55°F
1,577
Growing degree days, base 60°F
965

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23100
February99100
March80505
April578040
May3266185
June11160403
July6220679
August16173622
September16328325
October519067
November87505
December1,22700

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 10.4 km from Morgan 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 USC00425826 (Morgan). Public domain.