Skagway climate

Skagway Frost Dates and Growing Season

NOAA 1991-2020 normals for Skagway, 0.4 km from Skagway, elevation 35 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Skagway. 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 6 and the first fall freeze around October 1, a growing season of about 146 days.

Median at 36°F
last May 20, first September 22
Median at 32°F
last May 6, first October 1
Median at 28°F
last April 23, first October 15

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 3May 29May 26May 23May 20May 17May 14May 12May 7
32°FMay 22May 14May 11May 8May 6May 4May 1Apr 28Apr 24
28°FMay 13May 3Apr 30Apr 26Apr 23Apr 20Apr 16Apr 12Apr 6
24°FMay 10Apr 20Apr 14Apr 10Apr 6Apr 4Apr 1Mar 28Mar 20
20°FMay 5Apr 8Apr 2Mar 30Mar 26Mar 23Mar 18Mar 13Mar 5
16°FMay 1Mar 31Mar 25Mar 20Mar 16Mar 11Mar 7Feb 28Feb 12

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 6Sep 13Sep 17Sep 20Sep 22Sep 25Sep 28Oct 1Oct 5
32°FSep 15Sep 21Sep 26Sep 29Oct 1Oct 5Oct 8Oct 13Oct 19
28°FSep 21Oct 1Oct 5Oct 9Oct 15Oct 20Oct 24Oct 30Nov 5
24°FSep 22Oct 7Oct 22Oct 27Nov 1Nov 4Nov 8Nov 15Nov 22
20°FSep 22Oct 27Nov 2Nov 7Nov 12Nov 16Nov 22Nov 28Dec 4
16°FSep 22Nov 1Nov 10Nov 16Nov 23Nov 28Dec 2Dec 8Dec 19

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°F14313513112712211911410792
32°F168160155151146142136129105
28°F198190184177171166158150124
24°F231221214208201195184169140
20°F259248241234226218206185153
16°F289274264256248238224198158

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
8,490
Cooling degree days, base 65°F
11
Growing degree days, base 40°F
2,483
Growing degree days, base 45°F
1,578
Growing degree days, base 50°F
856
Growing degree days, base 55°F
333
Growing degree days, base 60°F
76

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24900
February1,05000
March1,03500
April71405
May454071
June2444212
July1885282
August2392229
September437054
October72104
November99600
December1,16300

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 0.4 km from Skagway. 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 USC00508525 (Skagway). Public domain.