Haines climate

Haines Frost Dates and Growing Season

NOAA 1991-2020 normals for Haines #2, 0.3 km from Haines, elevation 95 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Haines #2. 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 30 and the first fall freeze around October 7, a growing season of about 160 days.

Median at 36°F
last May 12, first September 27
Median at 32°F
last April 30, first October 7
Median at 28°F
last April 15, first October 24

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 24May 20May 18May 15May 12May 10May 7May 5May 1
32°FMay 13May 9May 5May 3Apr 30Apr 28Apr 24Apr 21Apr 16
28°FMay 4Apr 27Apr 22Apr 18Apr 15Apr 11Apr 9Apr 5Mar 31
24°FApr 17Apr 11Apr 7Apr 4Apr 3Mar 31Mar 29Mar 24Mar 17
20°FApr 4Apr 1Mar 30Mar 26Mar 23Mar 20Mar 14Mar 10Mar 2
16°FMar 29Mar 24Mar 20Mar 16Mar 12Mar 9Mar 4Feb 28Feb 18

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 15Sep 19Sep 22Sep 24Sep 27Sep 29Oct 1Oct 5Oct 9
32°FSep 24Sep 29Oct 1Oct 4Oct 7Oct 10Oct 13Oct 17Oct 22
28°FOct 5Oct 11Oct 16Oct 20Oct 24Oct 27Oct 30Nov 3Nov 10
24°FOct 23Oct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 23
20°FNov 4Nov 7Nov 10Nov 14Nov 18Nov 21Nov 24Nov 28Dec 5
16°FNov 9Nov 14Nov 17Nov 21Nov 25Nov 30Dec 4Dec 9Dec 17

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°F153147143140136132128124119
32°F180173168163160156152146141
28°F213206200195190186181176168
24°F241233227222218213209203195
20°F266256249244239235230225218
16°F289278270263257252246241234

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
8,837
Cooling degree days, base 65°F
13
Growing degree days, base 40°F
2,350
Growing degree days, base 45°F
1,477
Growing degree days, base 50°F
773
Growing degree days, base 55°F
287
Growing degree days, base 60°F
71

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,28600
February1,07400
March1,07100
April74004
May467069
June2695189
July2175253
August2603209
September446048
October74602
November1,05300
December1,20900

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 0.3 km from Haines. 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 USC00503502 (Haines #2). Public domain.