Washburn climate

Washburn Frost Dates and Growing Season

NOAA 1991-2020 normals for Washburn, 1 km from Washburn, elevation 1755 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Washburn. 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 12 and the first fall freeze around September 30, a growing season of about 140 days.

Median at 36°F
last May 22, first September 22
Median at 32°F
last May 12, first September 30
Median at 28°F
last May 3, first October 8

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 2May 30May 27May 24May 22May 19May 16May 14May 9
32°FMay 25May 20May 17May 14May 12May 9May 7May 4Apr 30
28°FMay 16May 11May 8May 5May 3Apr 30Apr 28Apr 24Apr 17
24°FMay 6May 2Apr 30Apr 26Apr 24Apr 20Apr 17Apr 14Apr 9
20°FApr 29Apr 23Apr 19Apr 16Apr 13Apr 10Apr 8Apr 4Apr 1
16°FApr 19Apr 14Apr 10Apr 7Apr 5Apr 3Mar 31Mar 26Mar 19

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 9Sep 14Sep 17Sep 19Sep 22Sep 24Sep 26Sep 28Oct 2
32°FSep 18Sep 22Sep 25Sep 27Sep 30Oct 2Oct 4Oct 7Oct 11
28°FSep 27Sep 30Oct 3Oct 5Oct 8Oct 11Oct 13Oct 16Oct 20
24°FOct 4Oct 9Oct 12Oct 14Oct 17Oct 20Oct 23Oct 26Oct 30
20°FOct 13Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 4Nov 9
16°FOct 23Oct 26Oct 29Nov 1Nov 3Nov 6Nov 9Nov 13Nov 18

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°F139133129126122119115111104
32°F157152147144140137133129123
28°F177170166162159155151147140
24°F195190185181176172168163157
20°F214207203199194191187182176
16°F231223218214211207203199192

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
8,676
Cooling degree days, base 65°F
463
Growing degree days, base 40°F
4,027
Growing degree days, base 45°F
3,072
Growing degree days, base 50°F
2,229
Growing degree days, base 55°F
1,501
Growing degree days, base 60°F
906

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,64100
February1,37100
March1,13002
April673035
May34213195
June9470428
July23178620
August42158581
September20841301
October633264
November1,05703
December1,46300

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 km from Washburn. 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 USC00329195 (Washburn). Public domain.