Douglass climate

Douglass Frost Dates and Growing Season

NOAA 1991-2020 normals for Smileyberg 1N, 11.7 km from Douglass, elevation 1330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Smileyberg 1N. 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 18 and the first fall freeze around October 21, a growing season of about 185 days.

Median at 36°F
last April 28, first October 11
Median at 32°F
last April 18, first October 21
Median at 28°F
last April 7, 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 10May 6May 3Apr 30Apr 28Apr 25Apr 22Apr 18Apr 13
32°FMay 2Apr 28Apr 24Apr 21Apr 18Apr 15Apr 12Apr 8Apr 3
28°FApr 23Apr 18Apr 14Apr 10Apr 7Apr 4Apr 1Mar 30Mar 22
24°FApr 12Apr 7Apr 4Apr 1Mar 30Mar 26Mar 21Mar 15Mar 9
20°FApr 4Mar 31Mar 26Mar 21Mar 17Mar 13Mar 9Mar 5Feb 28
16°FMar 27Mar 18Mar 13Mar 10Mar 6Mar 2Feb 28Feb 23Feb 17

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 6Oct 9Oct 11Oct 14Oct 17Oct 20Oct 24
32°FOct 5Oct 12Oct 15Oct 19Oct 21Oct 24Oct 27Oct 31Nov 4
28°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 2Nov 4Nov 7Nov 13
24°FOct 26Oct 30Nov 2Nov 4Nov 7Nov 11Nov 15Nov 19Nov 25
20°FNov 1Nov 6Nov 11Nov 15Nov 18Nov 21Nov 24Nov 29Dec 4
16°FNov 8Nov 16Nov 19Nov 23Nov 27Dec 1Dec 4Dec 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°F186179174170165163159154147
32°F206199193189185181176172165
28°F227220215210206202197192183
24°F250241235231227222216210203
20°F270262256250245240235229220
16°F288281275271266261255248238

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
5,013
Cooling degree days, base 65°F
1,324
Growing degree days, base 40°F
6,403
Growing degree days, base 45°F
5,110
Growing degree days, base 50°F
3,960
Growing degree days, base 55°F
2,951
Growing degree days, base 60°F
2,071

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06602
February848010
March644361
April34015192
May12181430
June9258699
July1408873
August2369832
September52163562
October29727246
November646149
December98705

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 11.7 km from Douglass. 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 USC00147534 (Smileyberg 1N). Public domain.