Hamilton County climate

Hamilton County Frost Dates and Growing Season

NOAA 1991-2020 normals for Indian Lake 2SW, 20.6 km from Hamilton County, elevation 1670 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Indian Lake 2SW. 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 23 and the first fall freeze around September 27, a growing season of about 125 days.

Median at 36°F
last June 3, first September 15
Median at 32°F
last May 23, first September 27
Median at 28°F
last May 9, first October 7

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 19Jun 12Jun 8Jun 6Jun 3May 31May 29May 26May 22
32°FJun 4May 31May 28May 25May 23May 20May 17May 13May 6
28°FMay 24May 19May 15May 12May 9May 5May 1Apr 29Apr 24
24°FMay 12May 6May 2Apr 29Apr 27Apr 23Apr 20Apr 17Apr 13
20°FApr 27Apr 22Apr 19Apr 16Apr 13Apr 11Apr 8Apr 6Apr 3
16°FApr 17Apr 12Apr 9Apr 7Apr 5Apr 4Apr 2Mar 31Mar 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 1Sep 5Sep 8Sep 11Sep 15Sep 18Sep 21Sep 25Sep 29
32°FSep 12Sep 17Sep 21Sep 24Sep 27Sep 29Oct 1Oct 4Oct 9
28°FSep 24Sep 30Oct 2Oct 5Oct 7Oct 10Oct 15Oct 19Oct 27
24°FOct 5Oct 10Oct 15Oct 19Oct 22Oct 25Oct 30Nov 2Nov 6
20°FOct 19Oct 25Oct 30Nov 1Nov 3Nov 6Nov 9Nov 13Nov 19
16°FNov 1Nov 3Nov 7Nov 10Nov 14Nov 17Nov 20Nov 24Nov 29

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°F12111511010610399959081
32°F146139134129125122117113106
28°F172165159155151147143137130
24°F197191186181177173169162154
20°F221215211207203199195190183
16°F241233229224221217213209203

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
8,865
Cooling degree days, base 65°F
140
Growing degree days, base 40°F
3,221
Growing degree days, base 45°F
2,316
Growing degree days, base 50°F
1,541
Growing degree days, base 55°F
904
Growing degree days, base 60°F
425

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,53100
February1,33600
March1,22001
April792014
May4326125
June17826305
July7855442
August10440402
September28113211
October639040
November95302
December1,32200

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 20.6 km from Hamilton 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 USC00304102 (Indian Lake 2SW). Public domain.