Eagle climate

Eagle Frost Dates and Growing Season

NOAA 1991-2020 normals for Sullivan 3SE, 11.5 km from Eagle, elevation 933 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sullivan 3SE. 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 3 and the first fall freeze around October 9, a growing season of about 157 days.

Median at 36°F
last May 16, first September 29
Median at 32°F
last May 3, first October 9
Median at 28°F
last April 22, first October 22

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 30May 25May 22May 19May 16May 13May 9May 5Apr 30
32°FMay 21May 15May 10May 6May 3Apr 30Apr 27Apr 23Apr 18
28°FMay 7May 2Apr 29Apr 26Apr 22Apr 19Apr 16Apr 12Apr 7
24°FApr 28Apr 21Apr 17Apr 14Apr 10Apr 7Apr 4Apr 1Mar 27
20°FApr 16Apr 9Apr 6Apr 3Mar 31Mar 28Mar 25Mar 21Mar 15
16°FApr 4Mar 31Mar 27Mar 24Mar 21Mar 18Mar 15Mar 12Mar 7

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 17Sep 21Sep 25Sep 27Sep 29Oct 2Oct 5Oct 8Oct 13
32°FSep 25Sep 29Oct 2Oct 6Oct 9Oct 12Oct 15Oct 20Oct 25
28°FOct 4Oct 11Oct 15Oct 18Oct 22Oct 25Oct 28Oct 31Nov 5
24°FOct 19Oct 24Oct 27Oct 31Nov 1Nov 4Nov 8Nov 12Nov 16
20°FNov 1Nov 3Nov 7Nov 10Nov 13Nov 16Nov 19Nov 22Nov 27
16°FNov 7Nov 12Nov 15Nov 18Nov 21Nov 24Nov 26Nov 30Dec 6

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°F157151146141137132128123117
32°F179171166161157154149143135
28°F202194189186181177172168159
24°F226217213208204200195190183
20°F247241236231227223219214208
16°F266258253248244240236231225

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
7,267
Cooling degree days, base 65°F
590
Growing degree days, base 40°F
4,583
Growing degree days, base 45°F
3,528
Growing degree days, base 50°F
2,600
Growing degree days, base 55°F
1,800
Growing degree days, base 60°F
1,122

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42300
February1,18801
March975010
April586262
May27333253
June60126516
July13202654
August21159603
September14960370
October4818116
November857015
December1,24101

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 11.5 km from Eagle. 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 USC00478316 (Sullivan 3SE). Public domain.