Kaplan climate

Kaplan Frost Dates and Growing Season

NOAA 1991-2020 normals for Leland Bowman Lock, 24.9 km from Kaplan, elevation 40 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Leland Bowman Lock. 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 February 17 and the first fall freeze around December 5, a growing season of about 298 days.

Median at 36°F
last March 5, first November 21
Median at 32°F
last February 17, first December 5
Median at 28°F
last January 29, first December 25

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°FMar 29Mar 21Mar 15Mar 9Mar 5Mar 1Feb 25Feb 20Feb 9
32°FMar 13Mar 5Feb 28Feb 24Feb 17Feb 10Feb 3Jan 29Jan 19
28°FFeb 28Feb 17Feb 9Feb 3Jan 29Jan 23Jan 16Jan 9Dec 30
24°FFeb 9Feb 2Jan 28Jan 22Jan 17Jan 11Jan 5Dec 31Dec 21
20°FFeb 2Jan 30Jan 24Jan 17Jan 13Jan 10Jan 5Jan 1Dec 22
16°F–––––––––

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°FNov 2Nov 7Nov 13Nov 17Nov 21Nov 26Dec 1Dec 4Dec 12
32°FNov 13Nov 20Nov 27Dec 1Dec 5Dec 11Dec 18Dec 27Jan 4
28°FNov 27Dec 4Dec 11Dec 17Dec 25Jan 1Jan 4Jan 12Jan 25
24°FDec 9Dec 17Dec 24Dec 31Jan 2Jan 6Jan 12Jan 21Feb 1
20°FDec 17Dec 30Jan 2Jan 6Jan 10Jan 14Jan 20Jan 26Feb 1
16°F–––––––––

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°F294283276269263256249241231
32°F334320312305298288281273258
28°F365354344336331324316305292
24°F365365365365365356347337327
20°F365365365365365365365365349
16°F365365365365365365365365365

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
99% of years
28°F or colder
89% of years
24°F or colder
57% of years
20°F or colder
21% of years
16°F or colder
4% 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
1,668
Cooling degree days, base 65°F
2,492
Growing degree days, base 40°F
9,986
Growing degree days, base 45°F
8,237
Growing degree days, base 50°F
6,576
Growing degree days, base 55°F
5,049
Growing degree days, base 60°F
3,678

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4623117
February3137161
March17934335
April60104495
May5285746
June0444894
July0510975
August0510975
September1385834
October43167590
November21033296
December39610158

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 24.9 km from Kaplan. 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 USC00165296 (Leland Bowman Lock). Public domain.