Dearborn climate

Dearborn Frost Dates and Growing Season

NOAA 1991-2020 normals for Kansas City Intl AP, 25.2 km from Dearborn, elevation 1005 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Kansas City Intl AP. 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 13 and the first fall freeze around October 24, a growing season of about 193 days.

Median at 36°F
last April 24, first October 14
Median at 32°F
last April 13, first October 24
Median at 28°F
last April 1, first November 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°FMay 7May 3Apr 30Apr 28Apr 24Apr 21Apr 17Apr 14Apr 9
32°FApr 29Apr 24Apr 20Apr 16Apr 13Apr 9Apr 6Apr 2Mar 30
28°FApr 18Apr 12Apr 7Apr 4Apr 1Mar 30Mar 26Mar 22Mar 16
24°FApr 6Apr 2Mar 30Mar 26Mar 22Mar 18Mar 15Mar 10Mar 5
20°FMar 31Mar 24Mar 19Mar 16Mar 12Mar 8Mar 5Mar 2Feb 25
16°FMar 20Mar 15Mar 10Mar 7Mar 4Mar 1Feb 26Feb 22Feb 15

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 29Oct 3Oct 7Oct 11Oct 14Oct 17Oct 19Oct 22Oct 26
32°FOct 9Oct 15Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 5
28°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 4Nov 6Nov 10Nov 16
24°FOct 29Nov 2Nov 5Nov 8Nov 10Nov 13Nov 16Nov 21Nov 29
20°FNov 4Nov 9Nov 13Nov 16Nov 20Nov 24Nov 28Dec 1Dec 6
16°FNov 11Nov 17Nov 22Nov 26Nov 30Dec 2Dec 6Dec 12Dec 17

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°F191184180175171167164158150
32°F212206200197193189185178171
28°F234226221217213208204199192
24°F257249243238232229224219212
20°F274267261257252247242236228
16°F295287280275270264261255247

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
5,071
Cooling degree days, base 65°F
1,363
Growing degree days, base 40°F
6,467
Growing degree days, base 45°F
5,180
Growing degree days, base 50°F
4,025
Growing degree days, base 55°F
3,004
Growing degree days, base 60°F
2,116

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11702
February879011
March639473
April33119200
May10998457
June7280723
July0409874
August2364828
September58158552
October29529245
November645254
December98906

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 25.2 km from Dearborn. 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 USW00003947 (Kansas City Intl AP). Public domain.