Scott County climate

Scott County Frost Dates and Growing Season

NOAA 1991-2020 normals for Davenport, 4.5 km from Scott County, elevation 754 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Davenport. 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 23 and the first fall freeze around October 15, a growing season of about 174 days.

Median at 36°F
last May 2, first October 4
Median at 32°F
last April 23, first October 15
Median at 28°F
last April 12, 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 17May 13May 9May 5May 2Apr 30Apr 27Apr 23Apr 17
32°FMay 8May 3Apr 30Apr 26Apr 23Apr 20Apr 16Apr 13Apr 8
28°FApr 30Apr 24Apr 20Apr 16Apr 12Apr 9Apr 6Apr 2Mar 29
24°FApr 19Apr 12Apr 8Apr 5Apr 2Mar 30Mar 26Mar 21Mar 15
20°FApr 7Apr 1Mar 29Mar 26Mar 22Mar 18Mar 14Mar 11Mar 6
16°FMar 29Mar 23Mar 19Mar 15Mar 13Mar 10Mar 7Mar 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 29Oct 1Oct 4Oct 6Oct 9Oct 13Oct 17
32°FOct 1Oct 5Oct 9Oct 12Oct 15Oct 17Oct 20Oct 24Oct 28
28°FOct 11Oct 17Oct 19Oct 22Oct 24Oct 27Oct 29Nov 1Nov 5
24°FOct 22Oct 26Oct 29Oct 31Nov 2Nov 5Nov 8Nov 11Nov 16
20°FNov 1Nov 5Nov 7Nov 10Nov 13Nov 16Nov 19Nov 23Nov 29
16°FNov 7Nov 12Nov 15Nov 18Nov 22Nov 25Nov 28Dec 1Dec 7

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°F173166161158154150146142135
32°F193186182177174170165160153
28°F214206202197193190184180173
24°F238231225219215211206200193
20°F259250245240236233228221215
16°F276268263258253248244240232

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
6,326
Cooling degree days, base 65°F
879
Growing degree days, base 40°F
5,382
Growing degree days, base 45°F
4,235
Growing degree days, base 50°F
3,209
Growing degree days, base 55°F
2,306
Growing degree days, base 60°F
1,525

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33400
February1,08502
March819233
April4478122
May17069373
June18201633
July4274735
August8217674
September10492441
October40216165
November776027
December1,15903

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 4.5 km from Scott County. 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 USW00094982 (Davenport). Public domain.