Snowflake climate

Snowflake Frost Dates and Growing Season

NOAA 1991-2020 normals for Snowflake, 0.8 km from Snowflake, elevation 5642 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Snowflake. 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 11 and the first fall freeze around October 10, a growing season of about 149 days.

Median at 36°F
last May 26, first October 2
Median at 32°F
last May 11, first October 10
Median at 28°F
last April 29, first October 20

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 12Jun 6Jun 3May 31May 26May 22May 18May 14May 10
32°FMay 31May 22May 17May 14May 11May 8May 5May 2Apr 27
28°FMay 15May 10May 6May 2Apr 29Apr 26Apr 22Apr 19Apr 12
24°FMay 3Apr 26Apr 20Apr 15Apr 11Apr 7Apr 3Mar 30Mar 22
20°FApr 14Apr 6Apr 2Mar 28Mar 23Mar 18Mar 14Mar 10Mar 5
16°FMar 26Mar 16Mar 11Mar 7Mar 3Mar 1Feb 25Feb 19Feb 8

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 20Sep 25Sep 27Oct 1Oct 2Oct 4Oct 5Oct 8Oct 13
32°FSep 28Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 18Oct 22
28°FOct 6Oct 10Oct 14Oct 18Oct 20Oct 23Oct 26Oct 29Nov 2
24°FOct 15Oct 20Oct 24Oct 27Oct 30Nov 1Nov 4Nov 7Nov 12
20°FOct 25Oct 31Nov 3Nov 6Nov 9Nov 11Nov 15Nov 18Nov 23
16°FNov 5Nov 10Nov 14Nov 18Nov 20Nov 23Nov 26Nov 30Dec 4

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°F148141136132127122117111104
32°F169162157152149145140135126
28°F193186182177172169164158150
24°F223216209204199194188182174
20°F253246240233229224218210202
16°F284275269264260255249242233

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
4,887
Cooling degree days, base 65°F
704
Growing degree days, base 40°F
5,476
Growing degree days, base 45°F
4,154
Growing degree days, base 50°F
3,034
Growing degree days, base 55°F
2,094
Growing degree days, base 60°F
1,319

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January92700
February72502
March619019
April414096
May19216297
June27123546
July1273738
August1220684
September4970471
October3331167
November657015
December94200

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 0.8 km from Snowflake. 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 USC00028012 (Snowflake). Public domain.