Johnson climate

Johnson Frost Dates and Growing Season

NOAA 1991-2020 normals for Johnson 2 N, 2.5 km from Johnson, elevation 980 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Johnson 2 N. 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 9 and the first fall freeze around October 1, a growing season of about 142 days.

Median at 36°F
last May 24, first September 21
Median at 32°F
last May 9, first October 1
Median at 28°F
last April 28, first October 13

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 7Jun 2May 31May 28May 24May 21May 18May 14May 9
32°FMay 24May 19May 15May 12May 9May 6May 3Apr 30Apr 27
28°FMay 11May 6May 3Apr 30Apr 28Apr 26Apr 24Apr 21Apr 17
24°FApr 29Apr 24Apr 21Apr 19Apr 16Apr 14Apr 11Apr 8Apr 5
20°FApr 19Apr 14Apr 11Apr 9Apr 7Apr 5Apr 4Apr 2Mar 30
16°FApr 11Apr 7Apr 5Apr 4Apr 2Apr 1Mar 30Mar 25Mar 20

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 9Sep 13Sep 16Sep 18Sep 21Sep 23Sep 25Sep 28Oct 2
32°FSep 19Sep 23Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
28°FSep 30Oct 3Oct 6Oct 9Oct 13Oct 16Oct 20Oct 24Oct 31
24°FOct 10Oct 17Oct 21Oct 24Oct 28Nov 1Nov 3Nov 6Nov 11
20°FOct 23Oct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 17Nov 21
16°FNov 5Nov 9Nov 12Nov 15Nov 18Nov 20Nov 23Nov 26Nov 30

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°F136130126121118114111106101
32°F162156150146142138134130124
28°F187180174170166162158153146
24°F211204200196192189185179171
20°F229224220216212208205200193
16°F247241236232229226222217211

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
8,684
Cooling degree days, base 65°F
183
Growing degree days, base 40°F
3,456
Growing degree days, base 45°F
2,529
Growing degree days, base 50°F
1,730
Growing degree days, base 55°F
1,056
Growing degree days, base 60°F
527

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57000
February1,34100
March1,20100
April750022
May3896153
June14834341
July5174488
August7848436
September26621237
October620047
November94107
December1,33000

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 2.5 km from Johnson. 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 USC00434290 (Johnson 2 N). Public domain.