Dayton climate

Dayton Frost Dates and Growing Season

NOAA 1991-2020 normals for Mcminnville Muni AP, 5.4 km from Dayton, elevation 159 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mcminnville Muni AP. 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 15 and the first fall freeze around October 26, a growing season of about 195 days.

Median at 36°F
last May 8, first October 7
Median at 32°F
last April 15, first October 26
Median at 28°F
last March 3, first November 16

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 29May 21May 16May 11May 8May 4Apr 30Apr 28Apr 21
32°FMay 6Apr 30Apr 26Apr 21Apr 15Apr 9Apr 2Mar 27Mar 18
28°FApr 8Mar 26Mar 17Mar 10Mar 3Feb 26Feb 22Feb 15Jan 28
24°FFeb 24Feb 16Feb 8Jan 30Jan 20Jan 10Jan 2Dec 23Dec 9
20°FFeb 12Jan 29Jan 15Jan 7Jan 1Dec 25Dec 17Dec 10Nov 30
16°FJan 16Jan 8Jan 2Dec 29Dec 23Dec 18Dec 13Dec 9Dec 5

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 21Sep 28Oct 1Oct 4Oct 7Oct 10Oct 15Oct 20Oct 27
32°FOct 5Oct 12Oct 17Oct 22Oct 26Oct 30Nov 3Nov 10Nov 19
28°FOct 22Oct 31Nov 6Nov 10Nov 16Nov 22Nov 29Dec 6Dec 17
24°FNov 10Nov 18Nov 26Dec 2Dec 9Dec 16Dec 24Jan 4Jan 22
20°FNov 24Dec 1Dec 7Dec 13Dec 18Dec 26Jan 1Jan 13Jan 31
16°FDec 2Dec 7Dec 10Dec 15Dec 20Dec 24Dec 29Jan 3Jan 15

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°F183172165158152146141134126
32°F230219210202195189182173162
28°F300286275266258250240229217
24°F365354344334327319310297282
20°F365365365365365358347338326
16°F365365365365365365365365351

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
88% of years
20°F or colder
45% of years
16°F or colder
15% 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
4,694
Cooling degree days, base 65°F
284
Growing degree days, base 40°F
4,882
Growing degree days, base 45°F
3,400
Growing degree days, base 50°F
2,240
Growing degree days, base 55°F
1,356
Growing degree days, base 60°F
704

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January73604
February61204
March577021
April448164
May2828201
June14525330
July30101536
August29107543
September11240379
October3692132
November593021
December76105

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 5.4 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 USW00094273 (Mcminnville Muni AP). Public domain.