Hoonah-Angoon Census Area climate

Hoonah-Angoon Census Area Frost Dates and Growing Season

NOAA 1991-2020 normals for Hoonah, 33.7 km from Hoonah-Angoon Census Area, elevation 130 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hoonah. 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 9 and the first fall freeze around October 4, a growing season of about 145 days.

Median at 32°F
last May 9, first October 4
Median at 28°F
last April 26, first October 19

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°F–––––––––
32°FJul 4Jun 3May 19May 13May 9May 5May 2Apr 30Apr 25
28°FJul 3May 31May 8May 1Apr 26Apr 21Apr 15Apr 10Apr 3
24°FJun 25May 14Apr 29Apr 18Apr 9Apr 2Mar 28Mar 21Mar 12
20°FApr 29Apr 7Mar 28Mar 21Mar 17Mar 12Mar 7Mar 1Feb 17
16°FMar 24Mar 16Mar 10Mar 6Mar 1Feb 23Feb 11Feb 2Jan 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°F–––––––––
32°FSep 1Sep 18Sep 26Sep 30Oct 4Oct 8Oct 14Oct 19Oct 26
28°FSep 2Sep 24Oct 2Oct 10Oct 19Oct 28Nov 3Nov 8Nov 15
24°FSep 7Sep 29Oct 9Oct 28Nov 8Nov 13Nov 18Nov 22Nov 28
20°FOct 1Nov 1Nov 14Nov 20Nov 25Nov 29Dec 4Dec 14Dec 27
16°FNov 23Nov 30Dec 4Dec 11Dec 21Dec 28Jan 4Jan 13Jan 25

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°F1451371311261201131049173
32°F17316515915314513712610483
28°F21220119118217416414712499
24°F247233224213202188169144117
20°F293278267258250242228205175
16°F338322309301293285278268257

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
99% 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
7,981
Cooling degree days, base 65°F
4
Growing degree days, base 40°F
2,356
Growing degree days, base 45°F
1,438
Growing degree days, base 50°F
735
Growing degree days, base 55°F
258
Growing degree days, base 60°F
48

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06800
February93200
March95600
April72201
May507043
June3142145
July2272241
August2351231
September411069
October68503
November90000
December1,02500

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 33.7 km from Hoonah-Angoon Census Area. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00503695 (Hoonah). Public domain.