Dayton climate

Dayton Frost Dates and Growing Season

NOAA 1991-2020 normals for Dayton, 0.2 km from Dayton, elevation 3920 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dayton. 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 May 24 and the first fall freeze around September 18, a growing season of about 114 days.

Median at 36°F
last June 7, first September 7
Median at 32°F
last May 24, first September 18
Median at 28°F
last May 9, first September 28

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°FJun 22Jun 17Jun 14Jun 10Jun 7Jun 4Jun 2May 29May 24
32°FJun 7Jun 2May 30May 26May 24May 21May 18May 15May 11
28°FMay 23May 18May 15May 12May 9May 7May 5May 2Apr 28
24°FMay 11May 6May 2Apr 30Apr 28Apr 25Apr 22Apr 17Apr 11
20°FMay 1Apr 27Apr 23Apr 19Apr 15Apr 12Apr 7Apr 3Mar 30
16°FApr 23Apr 16Apr 11Apr 6Apr 3Mar 31Mar 28Mar 22Mar 15

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°FAug 23Aug 29Sep 1Sep 4Sep 7Sep 10Sep 13Sep 16Sep 21
32°FSep 2Sep 8Sep 11Sep 15Sep 18Sep 20Sep 23Sep 27Oct 2
28°FSep 13Sep 19Sep 22Sep 25Sep 28Oct 1Oct 4Oct 8Oct 15
24°FSep 24Sep 28Oct 2Oct 5Oct 9Oct 14Oct 17Oct 21Oct 26
20°FOct 3Oct 8Oct 14Oct 18Oct 21Oct 24Oct 27Oct 31Nov 4
16°FOct 11Oct 18Oct 23Oct 26Oct 29Nov 1Nov 4Nov 8Nov 12

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°F10910398938985817668
32°F1351281231191141091059992
28°F162155148145140137132127119
24°F188180175171166161156151143
20°F209202196191187182178172164
16°F230222216211206202196191182

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
7,972
Cooling degree days, base 65°F
294
Growing degree days, base 40°F
3,652
Growing degree days, base 45°F
2,671
Growing degree days, base 50°F
1,854
Growing degree days, base 55°F
1,187
Growing degree days, base 60°F
662

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30000
February1,11902
March97706
April689026
May4274121
June17021310
July31130564
August56118528
September26619240
October637255
November99304
December1,30600

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 0.2 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 USC00482399 (Dayton). Public domain.