Johnson Siding climate

Johnson Siding Frost Dates and Growing Season

NOAA 1991-2020 normals for Johnson Siding, 0.3 km from Johnson Siding, elevation 4184 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Johnson Siding. 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 20 and the first fall freeze around September 25, a growing season of about 126 days.

Median at 36°F
last June 2, first September 15
Median at 32°F
last May 20, first September 25
Median at 28°F
last May 8, 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 18Jun 13Jun 8Jun 5Jun 2May 30May 27May 24May 19
32°FJun 3May 29May 26May 23May 20May 18May 15May 13May 9
28°FMay 22May 17May 13May 10May 8May 5May 2Apr 30Apr 25
24°FMay 9May 4May 1Apr 29Apr 27Apr 24Apr 21Apr 17Apr 12
20°FApr 30Apr 25Apr 22Apr 18Apr 15Apr 12Apr 9Apr 6Apr 1
16°FApr 21Apr 15Apr 11Apr 8Apr 5Apr 2Mar 30Mar 25Mar 18

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 1Sep 6Sep 9Sep 12Sep 15Sep 17Sep 20Sep 23Sep 27
32°FSep 11Sep 16Sep 20Sep 22Sep 25Sep 28Sep 30Oct 3Oct 7
28°FSep 21Sep 25Sep 29Oct 1Oct 4Oct 6Oct 9Oct 13Oct 17
24°FSep 29Oct 3Oct 7Oct 10Oct 13Oct 16Oct 20Oct 23Oct 27
20°FOct 8Oct 13Oct 17Oct 20Oct 22Oct 25Oct 28Nov 1Nov 6
16°FOct 15Oct 21Oct 25Oct 29Oct 31Nov 3Nov 6Nov 10Nov 15

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°F121115112108104100959183
32°F145138134130126123118113107
28°F166160156152148144141136130
24°F188182177173169165161156149
20°F209202197193190186181176168
16°F230223216212208203199194187

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
7,540
Cooling degree days, base 65°F
301
Growing degree days, base 40°F
3,748
Growing degree days, base 45°F
2,741
Growing degree days, base 50°F
1,904
Growing degree days, base 55°F
1,219
Growing degree days, base 60°F
682

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21800
February1,07900
March94905
April687025
May4263119
June15640342
July34136567
August4897515
September22425274
October609054
November91805
December1,19200

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 0.3 km from Johnson Siding. 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 USC00394343 (Johnson Siding). Public domain.