Dayton climate

Dayton Frost Dates and Growing Season

NOAA 1991-2020 normals for Dayton 2SE, 2.8 km from Dayton, elevation 822 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dayton 2SE. 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 4 and the first fall freeze around October 31, a growing season of about 208 days.

Median at 36°F
last April 18, first October 22
Median at 32°F
last April 4, first October 31
Median at 28°F
last March 26, first November 10

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 3Apr 29Apr 24Apr 21Apr 18Apr 14Apr 10Apr 6Mar 31
32°FApr 22Apr 16Apr 11Apr 7Apr 4Apr 1Mar 30Mar 25Mar 18
28°FApr 9Apr 4Apr 1Mar 29Mar 26Mar 22Mar 17Mar 14Mar 6
24°FMar 31Mar 26Mar 20Mar 16Mar 12Mar 8Mar 4Feb 27Feb 19
20°FMar 20Mar 13Mar 7Mar 2Feb 26Feb 20Feb 14Feb 6Jan 30
16°FMar 6Feb 28Feb 20Feb 13Feb 7Feb 1Jan 27Jan 20Jan 9

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 9Oct 14Oct 17Oct 20Oct 22Oct 24Oct 27Oct 30Nov 2
32°FOct 19Oct 22Oct 26Oct 28Oct 31Nov 1Nov 4Nov 8Nov 12
28°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 21Nov 29
24°FNov 6Nov 12Nov 15Nov 20Nov 24Nov 29Dec 2Dec 7Dec 16
20°FNov 16Nov 24Nov 30Dec 4Dec 8Dec 15Dec 23Dec 30Jan 7
16°FDec 1Dec 9Dec 19Dec 25Dec 31Jan 3Jan 7Jan 13Jan 22

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°F209202197192187183178174167
32°F229222216212208204200195187
28°F255246240234230226221215208
24°F287276270264258252246239231
20°F322311303295289282275267255
16°F354340332325319311303295282

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
95% 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
3,762
Cooling degree days, base 65°F
1,385
Growing degree days, base 40°F
7,137
Growing degree days, base 45°F
5,671
Growing degree days, base 50°F
4,363
Growing degree days, base 55°F
3,217
Growing degree days, base 60°F
2,225

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January842017
February652024
March4902103
April22524275
May65111513
June3275721
July0381846
August0361826
September21197626
October20732308
November505179
December751026

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 2.8 km from Dayton. 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 USC00402360 (Dayton 2SE). Public domain.