Henefer climate

Henefer Frost Dates and Growing Season

NOAA 1991-2020 normals for Echo Dam, 7.9 km from Henefer, elevation 5470 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Echo Dam. 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 30 and the first fall freeze around September 18, a growing season of about 112 days.

Median at 36°F
last June 15, first September 8
Median at 32°F
last May 30, first September 18
Median at 28°F
last May 10, first October 1

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 30Jun 24Jun 21Jun 18Jun 15Jun 12Jun 8Jun 4May 31
32°FJun 16Jun 10Jun 5Jun 1May 30May 26May 22May 17May 11
28°FMay 31May 24May 18May 14May 10May 7May 4Apr 30Apr 25
24°FMay 13May 7May 3Apr 30Apr 26Apr 22Apr 18Apr 13Apr 8
20°FApr 27Apr 20Apr 16Apr 11Apr 8Apr 4Apr 1Mar 27Mar 17
16°FApr 12Apr 5Mar 31Mar 26Mar 21Mar 16Mar 12Mar 9Mar 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°FAug 23Aug 31Sep 2Sep 6Sep 8Sep 11Sep 14Sep 18Sep 22
32°FSep 4Sep 9Sep 13Sep 15Sep 18Sep 21Sep 24Sep 27Oct 1
28°FSep 17Sep 21Sep 25Sep 27Oct 1Oct 3Oct 5Oct 9Oct 14
24°FSep 29Oct 2Oct 5Oct 8Oct 11Oct 15Oct 17Oct 22Oct 26
20°FOct 10Oct 15Oct 19Oct 21Oct 24Oct 27Oct 30Nov 2Nov 6
16°FOct 20Oct 25Oct 28Oct 31Nov 3Nov 6Nov 10Nov 13Nov 18

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°F1039692878379756962
32°F1321241201161121061019688
28°F161155150145141136131124116
24°F191184178173169164159153144
20°F222212206202196193188182173
16°F249240234230224219213207198

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
7,108
Cooling degree days, base 65°F
348
Growing degree days, base 40°F
4,050
Growing degree days, base 45°F
2,984
Growing degree days, base 50°F
2,091
Growing degree days, base 55°F
1,362
Growing degree days, base 60°F
778

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,28200
February1,02800
March82603
April599028
May3602152
June12638366
July14164615
August22125567
September18219297
October536059
November89003
December1,24300

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 7.9 km from Henefer. 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 USC00422385 (Echo Dam). Public domain.