Green Mountain Falls climate

Green Mountain Falls Frost Dates and Growing Season

NOAA 1991-2020 normals for Ruxton Park, 11 km from Green Mountain Falls, elevation 9060 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ruxton Park. 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 3 and the first fall freeze around September 17, a growing season of about 102 days.

Median at 32°F
last June 3, first September 17
Median at 28°F
last May 22, first September 28

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°F–––––––––
32°FJun 23Jun 15Jun 10Jun 6Jun 3May 31May 29May 25May 21
28°FJun 6Jun 2May 29May 25May 22May 19May 16May 13May 9
24°FMay 26May 21May 16May 13May 11May 8May 6May 3Apr 30
20°FMay 17May 12May 8May 5May 2Apr 30Apr 26Apr 21Apr 16
16°FMay 8May 3Apr 29Apr 25Apr 21Apr 17Apr 13Apr 8Apr 3

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°F–––––––––
32°FAug 30Sep 5Sep 10Sep 13Sep 17Sep 20Sep 23Sep 26Sep 30
28°FSep 11Sep 17Sep 22Sep 25Sep 28Sep 30Oct 3Oct 7Oct 12
24°FSep 21Sep 27Oct 1Oct 4Oct 8Oct 11Oct 14Oct 17Oct 21
20°FOct 1Oct 6Oct 10Oct 13Oct 16Oct 18Oct 21Oct 25Oct 31
16°FOct 10Oct 16Oct 19Oct 21Oct 24Oct 27Oct 30Nov 3Nov 8

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°F968882777166615445
32°F12011411010610297918675
28°F147141136131127122118113107
24°F169162157153148144139132124
20°F188181176171167162158153146
16°F209200195190186182178173165

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
8,583
Cooling degree days, base 65°F
18
Growing degree days, base 40°F
2,584
Growing degree days, base 45°F
1,695
Growing degree days, base 50°F
986
Growing degree days, base 55°F
459
Growing degree days, base 60°F
139

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22000
February1,07800
March1,00801
April80906
May584047
June2676210
July1579320
August2182253
September3761129
October690020
November96801
December1,21100

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 km from Green Mountain Falls. 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 USC00057309 (Ruxton Park). Public domain.