Overton climate

Overton Frost Dates and Growing Season

NOAA 1991-2020 normals for Henderson, 20 km from Overton, elevation 420 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Henderson. 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 15 and the first fall freeze around November 16, a growing season of about 247 days.

Median at 36°F
last March 29, first November 5
Median at 32°F
last March 15, first November 16
Median at 28°F
last March 1, first November 29

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 9Apr 5Apr 1Mar 29Mar 25Mar 20Mar 15Mar 7
32°FApr 3Mar 27Mar 23Mar 19Mar 15Mar 10Mar 5Mar 2Feb 24
28°FMar 21Mar 14Mar 9Mar 5Mar 1Feb 25Feb 20Feb 13Jan 31
24°FMar 9Mar 3Feb 25Feb 17Feb 9Feb 3Jan 29Jan 20Jan 9
20°FMar 1Feb 14Feb 5Feb 1Jan 26Jan 18Jan 10Jan 3Dec 21
16°FFeb 9Feb 4Jan 31Jan 25Jan 18Jan 12Jan 7Jan 3Dec 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°FOct 24Oct 29Oct 31Nov 2Nov 5Nov 8Nov 12Nov 16Nov 22
32°FNov 1Nov 5Nov 8Nov 12Nov 16Nov 20Nov 25Dec 1Dec 5
28°FNov 8Nov 14Nov 20Nov 25Nov 29Dec 3Dec 8Dec 15Dec 26
24°FNov 19Nov 27Dec 2Dec 8Dec 18Dec 25Jan 1Jan 7Jan 18
20°FNov 30Dec 11Dec 22Dec 30Jan 3Jan 8Jan 14Jan 23Feb 3
16°FDec 18Dec 28Jan 2Jan 5Jan 9Jan 15Jan 23Jan 31Feb 5

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°F249240232227223217212206198
32°F275264258252247241236229220
28°F308297289282275268262255244
24°F354338329321310304296286273
20°F365365365358348339332323307
16°F365365365365365365365359339

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
97% of years
20°F or colder
71% of years
16°F or colder
29% 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
2,215
Cooling degree days, base 65°F
2,477
Growing degree days, base 40°F
9,478
Growing degree days, base 45°F
7,795
Growing degree days, base 50°F
6,234
Growing degree days, base 55°F
4,822
Growing degree days, base 60°F
3,566

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January561483
February4098119
March26029272
April9688447
May14252702
June0440889
July05531,018
August05641,029
September5372817
October79135524
November29326231
December4996104

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 km from Overton. 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 USC00414081 (Henderson). Public domain.