Graham County climate

Graham County Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Thomas 2 Sw, 12.5 km from Graham County, elevation 2835 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Thomas 2 Sw. 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 1 and the first fall freeze around November 6, a growing season of about 217 days.

Median at 36°F
last April 17, first October 29
Median at 32°F
last April 1, first November 6
Median at 28°F
last March 13, first November 16

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 4Apr 29Apr 24Apr 21Apr 17Apr 14Apr 10Apr 7Apr 2
32°FApr 18Apr 11Apr 7Apr 4Apr 1Mar 29Mar 25Mar 20Mar 15
28°FApr 3Mar 28Mar 22Mar 17Mar 13Mar 10Mar 6Mar 2Feb 24
24°FMar 15Mar 7Mar 4Feb 28Feb 25Feb 20Feb 14Feb 7Jan 30
20°FMar 1Feb 20Feb 14Feb 7Feb 2Jan 29Jan 22Jan 13Dec 31
16°FFeb 14Feb 3Jan 28Jan 20Jan 12Jan 4Dec 30Dec 21Dec 11

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°FOct 15Oct 20Oct 23Oct 25Oct 29Nov 1Nov 3Nov 6Nov 10
32°FOct 21Oct 27Oct 31Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19
28°FOct 30Nov 5Nov 9Nov 13Nov 16Nov 18Nov 21Nov 24Nov 29
24°FNov 11Nov 16Nov 19Nov 22Nov 26Nov 29Dec 2Dec 5Dec 11
20°FNov 20Nov 25Nov 30Dec 2Dec 6Dec 10Dec 15Dec 20Dec 28
16°FNov 27Dec 3Dec 10Dec 15Dec 21Dec 25Jan 1Jan 6Jan 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°F214207201197193188184179171
32°F240232227222217213208203195
28°F267260254249244239234227218
24°F301290284278274269263257248
20°F345332324317310302295287277
16°F365365359352344338332324312

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
99% of years
16°F or colder
78% 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
2,592
Cooling degree days, base 65°F
2,431
Growing degree days, base 40°F
9,018
Growing degree days, base 45°F
7,340
Growing degree days, base 50°F
5,841
Growing degree days, base 55°F
4,535
Growing degree days, base 60°F
3,403

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January629013
February449051
March2984191
April11249389
May20222667
June0486936
July06291,094
August05641,029
September1377827
October7095492
November3644137
December648015

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 12.5 km from Graham County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00023150 (Ft Thomas 2 Sw). Public domain.