Kirkwood climate

Kirkwood Frost Dates and Growing Season

NOAA 1991-2020 normals for Monmouth 4NW, 8.1 km from Kirkwood, elevation 724 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Monmouth 4NW. 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 April 22 and the first fall freeze around October 14, a growing season of about 174 days.

Median at 36°F
last May 2, first October 5
Median at 32°F
last April 22, first October 14
Median at 28°F
last April 11, first October 24

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°FMay 15May 11May 8May 4May 2Apr 30Apr 27Apr 23Apr 19
32°FMay 7May 1Apr 29Apr 24Apr 22Apr 19Apr 16Apr 12Apr 7
28°FApr 26Apr 21Apr 18Apr 14Apr 11Apr 8Apr 5Apr 2Mar 29
24°FApr 17Apr 10Apr 7Apr 4Apr 1Mar 31Mar 27Mar 21Mar 15
20°FApr 6Apr 2Mar 30Mar 26Mar 22Mar 18Mar 15Mar 11Mar 6
16°FMar 30Mar 23Mar 19Mar 15Mar 12Mar 9Mar 6Mar 3Feb 27

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 19Sep 25Sep 28Oct 1Oct 5Oct 7Oct 10Oct 13Oct 17
32°FSep 29Oct 4Oct 9Oct 12Oct 14Oct 16Oct 19Oct 22Oct 27
28°FOct 10Oct 15Oct 19Oct 22Oct 24Oct 27Oct 29Nov 1Nov 6
24°FOct 21Oct 25Oct 29Nov 1Nov 2Nov 5Nov 9Nov 13Nov 18
20°FNov 1Nov 3Nov 6Nov 10Nov 13Nov 17Nov 21Nov 24Nov 29
16°FNov 7Nov 12Nov 17Nov 21Nov 24Nov 28Dec 1Dec 5Dec 11

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°F173167162158155151147143136
32°F193187182178174170166160154
28°F215208203199195191187182176
24°F238230224220215211207202196
20°F261252246241237232227221214
16°F280270265260256251246241233

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
6,319
Cooling degree days, base 65°F
887
Growing degree days, base 40°F
5,402
Growing degree days, base 45°F
4,256
Growing degree days, base 50°F
3,232
Growing degree days, base 55°F
2,325
Growing degree days, base 60°F
1,540

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33300
February1,08402
March832130
April4468128
May17169373
June22199627
July4273733
August8222679
September97100457
October39415174
November773028
December1,15602

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 8.1 km from Kirkwood. 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 USC00115772 (Monmouth 4NW). Public domain.