Hayden climate

Hayden Frost Dates and Growing Season

NOAA 1991-2020 normals for Hayden, 0.3 km from Hayden, elevation 6467 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hayden. 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 June 1 and the first fall freeze around September 20, a growing season of about 109 days.

Median at 36°F
last June 17, first September 10
Median at 32°F
last June 1, first September 20
Median at 28°F
last May 13, first September 29

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°FJul 3Jun 27Jun 23Jun 20Jun 17Jun 14Jun 10Jun 7Jun 2
32°FJun 16Jun 11Jun 7Jun 3Jun 1May 28May 25May 20May 15
28°FJun 1May 25May 20May 16May 13May 10May 7May 3Apr 29
24°FMay 15May 10May 6May 2Apr 29Apr 26Apr 23Apr 19Apr 14
20°FMay 3Apr 28Apr 24Apr 20Apr 15Apr 12Apr 8Apr 4Mar 30
16°FApr 22Apr 14Apr 9Apr 5Apr 2Mar 30Mar 25Mar 19Mar 15

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 27Sep 1Sep 4Sep 8Sep 10Sep 13Sep 15Sep 18Sep 22
32°FSep 7Sep 11Sep 14Sep 17Sep 20Sep 22Sep 25Sep 27Sep 30
28°FSep 16Sep 21Sep 24Sep 26Sep 29Oct 1Oct 4Oct 8Oct 13
24°FSep 26Sep 30Oct 3Oct 7Oct 10Oct 13Oct 16Oct 19Oct 24
20°FOct 5Oct 12Oct 15Oct 17Oct 20Oct 24Oct 27Oct 30Nov 4
16°FOct 16Oct 20Oct 24Oct 27Oct 30Nov 2Nov 5Nov 9Nov 14

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°F1029692888581767163
32°F1291231171141091051019688
28°F157150146142138134129124116
24°F183176171166163159154149141
20°F207200196191187182176171162
16°F232224218213208204199194185

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
7,943
Cooling degree days, base 65°F
206
Growing degree days, base 40°F
3,674
Growing degree days, base 45°F
2,682
Growing degree days, base 50°F
1,831
Growing degree days, base 55°F
1,130
Growing degree days, base 60°F
582

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42300
February1,16100
March95501
April645021
May3901130
June13824339
July20107552
August3668498
September2216251
October600039
November97401
December1,38300

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 Hayden. 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 USC00053867 (Hayden). Public domain.