Stratton climate

Stratton Frost Dates and Growing Season

NOAA 1991-2020 normals for Stratton, 0.4 km from Stratton, elevation 4399 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stratton. 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 6 and the first fall freeze around October 9, a growing season of about 155 days.

Median at 36°F
last May 15, first September 30
Median at 32°F
last May 6, first October 9
Median at 28°F
last April 27, 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°FMay 26May 22May 19May 17May 15May 13May 10May 8May 5
32°FMay 17May 13May 10May 8May 6May 3May 1Apr 29Apr 24
28°FMay 8May 4May 1Apr 29Apr 27Apr 24Apr 21Apr 18Apr 14
24°FApr 29Apr 24Apr 21Apr 19Apr 16Apr 13Apr 10Apr 6Apr 2
20°FApr 20Apr 15Apr 11Apr 8Apr 5Apr 2Mar 30Mar 25Mar 17
16°FApr 10Apr 5Apr 1Mar 29Mar 25Mar 20Mar 15Mar 9Mar 4

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 18Sep 22Sep 25Sep 28Sep 30Oct 3Oct 5Oct 8Oct 12
32°FSep 26Sep 30Oct 3Oct 6Oct 9Oct 12Oct 15Oct 17Oct 21
28°FOct 5Oct 10Oct 13Oct 16Oct 19Oct 21Oct 23Oct 26Oct 29
24°FOct 13Oct 17Oct 21Oct 24Oct 26Oct 29Nov 1Nov 4Nov 9
20°FOct 21Oct 26Oct 30Nov 1Nov 4Nov 7Nov 10Nov 14Nov 20
16°FOct 28Nov 2Nov 6Nov 10Nov 13Nov 17Nov 22Nov 26Dec 1

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°F152147144140137134130125120
32°F171165161158155151148143137
28°F192185180176173170165162156
24°F213206200196192189185180173
20°F236226221217212208203198191
16°F260251243238233228223216208

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
5,821
Cooling degree days, base 65°F
901
Growing degree days, base 40°F
5,397
Growing degree days, base 45°F
4,195
Growing degree days, base 50°F
3,146
Growing degree days, base 55°F
2,253
Growing degree days, base 60°F
1,508

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07402
February90004
March737029
April499294
May22332296
June40177587
July6320779
August9267722
September10696447
October4167155
November765028
December1,04603

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 0.4 km from Stratton. 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 USC00058008 (Stratton). Public domain.