Eagle River climate

Eagle River Frost Dates and Growing Season

NOAA 1991-2020 normals for Eagle Rvr, 1 km from Eagle River, elevation 1623 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Eagle Rvr. 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 25 and the first fall freeze around September 24, a growing season of about 121 days.

Median at 36°F
last June 4, first September 12
Median at 32°F
last May 25, first September 24
Median at 28°F
last May 13, first October 5

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 20Jun 14Jun 10Jun 7Jun 4Jun 1May 29May 26May 23
32°FJun 6Jun 2May 30May 27May 25May 22May 20May 16May 10
28°FMay 26May 22May 18May 16May 13May 10May 7May 4Apr 30
24°FMay 15May 11May 8May 5May 2Apr 30Apr 28Apr 24Apr 19
20°FMay 6May 1Apr 28Apr 25Apr 22Apr 19Apr 16Apr 13Apr 8
16°FApr 26Apr 22Apr 18Apr 15Apr 13Apr 10Apr 7Apr 4Mar 31

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°FAug 26Sep 1Sep 5Sep 9Sep 12Sep 15Sep 18Sep 22Sep 27
32°FSep 8Sep 14Sep 18Sep 21Sep 24Sep 27Oct 1Oct 3Oct 7
28°FSep 20Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15Oct 20
24°FOct 2Oct 7Oct 11Oct 14Oct 17Oct 21Oct 24Oct 29Nov 3
20°FOct 15Oct 21Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 13
16°FOct 28Nov 1Nov 4Nov 6Nov 8Nov 12Nov 14Nov 17Nov 22

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°F1181111061019793888373
32°F141134129125121117113108101
28°F163156152147144140136132124
24°F187180174170166162157152145
20°F211203199195191187183178171
16°F229222218213209206202198192

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
9,290
Cooling degree days, base 65°F
227
Growing degree days, base 40°F
3,370
Growing degree days, base 45°F
2,491
Growing degree days, base 50°F
1,723
Growing degree days, base 55°F
1,076
Growing degree days, base 60°F
568

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65200
February1,41400
March1,23403
April803017
May40610155
June13052376
July6191496
August9655425
September29217213
October689137
November1,06102
December1,45500

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 Eagle River. 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 USC00472314 (Eagle Rvr). Public domain.