Bethany climate

Bethany Frost Dates and Growing Season

NOAA 1991-2020 normals for Bethany, 1.2 km from Bethany, elevation 949 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bethany. 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 16 and the first fall freeze around October 22, a growing season of about 186 days.

Median at 36°F
last April 29, first October 12
Median at 32°F
last April 16, first October 22
Median at 28°F
last April 5, first October 31

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 13May 8May 5May 2Apr 29Apr 26Apr 22Apr 18Apr 13
32°FMay 3Apr 27Apr 23Apr 19Apr 16Apr 13Apr 9Apr 5Apr 1
28°FApr 21Apr 15Apr 11Apr 7Apr 5Apr 2Mar 31Mar 27Mar 22
24°FApr 11Apr 6Apr 2Mar 30Mar 28Mar 24Mar 21Mar 17Mar 11
20°FApr 4Mar 30Mar 26Mar 21Mar 18Mar 14Mar 10Mar 6Mar 2
16°FMar 27Mar 20Mar 16Mar 12Mar 9Mar 6Mar 3Feb 28Feb 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°FSep 26Oct 1Oct 4Oct 9Oct 12Oct 14Oct 17Oct 20Oct 25
32°FOct 6Oct 13Oct 16Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2
28°FOct 18Oct 22Oct 25Oct 29Oct 31Nov 2Nov 5Nov 8Nov 13
24°FOct 28Nov 1Nov 3Nov 6Nov 9Nov 11Nov 14Nov 17Nov 26
20°FNov 3Nov 8Nov 11Nov 14Nov 17Nov 20Nov 24Nov 29Dec 4
16°FNov 10Nov 15Nov 18Nov 22Nov 26Nov 30Dec 3Dec 8Dec 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°F187179173169165160156152145
32°F205200195191186183178173165
28°F227221216212208204200196188
24°F248241237231226222218212204
20°F267258253248244240236230221
16°F285276271266261257252246238

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
5,848
Cooling degree days, base 65°F
1,087
Growing degree days, base 40°F
5,801
Growing degree days, base 45°F
4,601
Growing degree days, base 50°F
3,530
Growing degree days, base 55°F
2,587
Growing degree days, base 60°F
1,770

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24600
February1,00204
March758242
April4088144
May15762379
June14223658
July1353817
August4298759
September81122493
October35318198
November728135
December1,09402

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 1.2 km from Bethany. 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 USC00230608 (Bethany). Public domain.