Sundance climate

Sundance Frost Dates and Growing Season

NOAA 1991-2020 normals for Sundance, 1.7 km from Sundance, elevation 4695 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sundance. 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 21 and the first fall freeze around September 25, a growing season of about 124 days.

Median at 36°F
last June 1, first September 16
Median at 32°F
last May 21, first September 25
Median at 28°F
last May 9, first October 4

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 24Jun 15Jun 8Jun 4Jun 1May 30May 27May 24May 20
32°FJun 5May 30May 27May 24May 21May 19May 16May 13May 9
28°FMay 23May 18May 15May 12May 9May 7May 4May 1Apr 27
24°FMay 12May 7May 3May 1Apr 29Apr 26Apr 22Apr 19Apr 14
20°FMay 1Apr 27Apr 24Apr 20Apr 17Apr 13Apr 10Apr 6Apr 1
16°FApr 22Apr 17Apr 12Apr 9Apr 6Apr 3Mar 30Mar 25Mar 16

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 29Sep 3Sep 7Sep 12Sep 16Sep 19Sep 22Sep 25Sep 29
32°FSep 7Sep 15Sep 19Sep 22Sep 25Sep 28Oct 1Oct 4Oct 8
28°FSep 18Sep 25Sep 29Oct 1Oct 4Oct 6Oct 9Oct 13Oct 19
24°FSep 27Oct 2Oct 5Oct 9Oct 12Oct 15Oct 18Oct 22Oct 26
20°FOct 4Oct 10Oct 14Oct 17Oct 21Oct 23Oct 27Oct 30Nov 4
16°FOct 11Oct 18Oct 23Oct 25Oct 29Nov 1Nov 4Nov 8Nov 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°F12211511010610196918574
32°F144137132128124120114109101
28°F165158154150145142137131123
24°F187180175170166162157152144
20°F208200195190186182178171163
16°F232224217211206202197191182

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
8,038
Cooling degree days, base 65°F
362
Growing degree days, base 40°F
3,722
Growing degree days, base 45°F
2,770
Growing degree days, base 50°F
1,959
Growing degree days, base 55°F
1,284
Growing degree days, base 60°F
747

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30400
February1,15100
March98606
April729024
May4425131
June16544338
July40156581
August54125538
September23831277
October646160
November98605
December1,29900

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 1.7 km from Sundance. 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 USC00488705 (Sundance). Public domain.