Heath climate

Heath Frost Dates and Growing Season

NOAA 1991-2020 normals for Lavon Dam, 22.1 km from Heath, elevation 510 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lavon 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 10 and the first fall freeze around November 19, a growing season of about 254 days.

Median at 36°F
last March 26, first November 8
Median at 32°F
last March 10, first November 19
Median at 28°F
last February 26, first December 1

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 16Apr 7Apr 3Mar 30Mar 26Mar 20Mar 15Mar 11Mar 4
32°FMar 31Mar 23Mar 18Mar 13Mar 10Mar 6Mar 2Feb 26Feb 20
28°FMar 17Mar 11Mar 5Mar 2Feb 26Feb 23Feb 18Feb 13Feb 1
24°FMar 7Feb 28Feb 23Feb 17Feb 10Feb 5Jan 30Jan 23Jan 12
20°FFeb 25Feb 17Feb 9Feb 2Jan 28Jan 20Jan 13Jan 5Dec 25
16°FFeb 17Feb 9Feb 2Jan 26Jan 20Jan 13Jan 9Jan 2Dec 25

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 25Oct 31Nov 2Nov 5Nov 8Nov 12Nov 15Nov 20Nov 25
32°FNov 1Nov 7Nov 12Nov 15Nov 19Nov 23Nov 27Dec 1Dec 5
28°FNov 13Nov 18Nov 23Nov 27Dec 1Dec 4Dec 8Dec 12Dec 22
24°FNov 24Nov 30Dec 5Dec 10Dec 15Dec 22Dec 29Jan 4Jan 16
20°FDec 6Dec 14Dec 22Dec 28Jan 1Jan 7Jan 13Jan 24Feb 5
16°FDec 18Dec 28Jan 1Jan 5Jan 11Jan 17Jan 24Feb 2Feb 14

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°F255246239233228223217211202
32°F278270264259254248243236227
28°F307296290284278273266260252
24°F341330321313307302295287276
20°F365365356347340332325315306
16°F365365365365365365359347333

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
78% of years
16°F or colder
34% 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
2,577
Cooling degree days, base 65°F
2,318
Growing degree days, base 40°F
9,015
Growing degree days, base 45°F
7,384
Growing degree days, base 50°F
5,884
Growing degree days, base 55°F
4,535
Growing degree days, base 60°F
3,344

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January653142
February474382
March30619230
April11763402
May19217663
June0429879
July05521,017
August05631,027
September6345789
October87111493
November32515195
December589266

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 22.1 km from Heath. 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 USC00415094 (Lavon Dam). Public domain.