Forest Hill climate

Forest Hill Frost Dates and Growing Season

NOAA 1991-2020 normals for Benbrook Dam, 16.6 km from Forest Hill, elevation 790 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Benbrook Dam. 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 March 14 and the first fall freeze around November 16, a growing season of about 245 days.

Median at 36°F
last March 30, first November 6
Median at 32°F
last March 14, first November 16
Median at 28°F
last March 2, first November 30

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°FApr 18Apr 11Apr 5Apr 2Mar 30Mar 25Mar 20Mar 16Mar 9
32°FApr 3Mar 29Mar 23Mar 18Mar 14Mar 11Mar 6Mar 2Feb 25
28°FMar 21Mar 14Mar 10Mar 6Mar 2Feb 27Feb 23Feb 18Feb 10
24°FMar 10Mar 3Feb 27Feb 22Feb 16Feb 10Feb 5Jan 31Jan 21
20°FFeb 26Feb 18Feb 12Feb 6Feb 1Jan 28Jan 21Jan 12Dec 31
16°FFeb 15Feb 8Feb 2Jan 28Jan 20Jan 15Jan 6Jan 1Dec 22

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 23Oct 27Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 22
32°FOct 31Nov 5Nov 9Nov 12Nov 16Nov 20Nov 25Nov 30Dec 5
28°FNov 8Nov 14Nov 20Nov 26Nov 30Dec 3Dec 7Dec 13Dec 21
24°FNov 19Nov 29Dec 3Dec 8Dec 13Dec 20Dec 25Jan 1Jan 9
20°FDec 5Dec 13Dec 19Dec 24Dec 30Jan 4Jan 11Jan 18Feb 1
16°FDec 14Dec 21Dec 29Jan 2Jan 7Jan 14Jan 20Jan 30Feb 6

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°F245238232227222216211206198
32°F271263256250245241236229220
28°F302292284278272266260253244
24°F335325315307302295286278269
20°F365355347339334326319309297
16°F365365365365362354347337325

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
99% of years
20°F or colder
88% of years
16°F or colder
55% 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
2,278
Cooling degree days, base 65°F
2,691
Growing degree days, base 40°F
9,654
Growing degree days, base 45°F
7,983
Growing degree days, base 50°F
6,430
Growing degree days, base 55°F
5,024
Growing degree days, base 60°F
3,772

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January589165
February4276112
March26629267
April9390452
May12270722
June0489939
July06231,088
August06231,088
September4387832
October74146542
November28824232
December525390

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 16.6 km from Forest Hill. 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 USC00410691 (Benbrook Dam). Public domain.