Middletown climate

Middletown Frost Dates and Growing Season

NOAA 1991-2020 normals for Wilmington New Castle CO AP, 26.7 km from Middletown, elevation 79 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wilmington New Castle CO 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 7 and the first fall freeze around November 1, a growing season of about 209 days.

Median at 36°F
last April 21, first October 22
Median at 32°F
last April 7, first November 1
Median at 28°F
last March 27, first November 14

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 1Apr 27Apr 23Apr 21Apr 18Apr 16Apr 12Apr 7
32°FApr 21Apr 16Apr 12Apr 10Apr 7Apr 4Apr 2Mar 31Mar 26
28°FApr 9Apr 4Apr 1Mar 31Mar 27Mar 24Mar 20Mar 17Mar 11
24°FMar 29Mar 24Mar 21Mar 18Mar 15Mar 12Mar 9Mar 4Feb 27
20°FMar 19Mar 14Mar 10Mar 7Mar 4Mar 1Feb 25Feb 19Feb 12
16°FMar 10Mar 4Feb 28Feb 23Feb 18Feb 13Feb 8Feb 4Jan 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°FOct 8Oct 13Oct 16Oct 19Oct 22Oct 24Oct 27Oct 31Nov 3
32°FOct 19Oct 24Oct 28Oct 31Nov 1Nov 4Nov 7Nov 11Nov 15
28°FNov 1Nov 4Nov 7Nov 11Nov 14Nov 16Nov 20Nov 25Dec 1
24°FNov 11Nov 15Nov 20Nov 24Nov 28Dec 1Dec 4Dec 8Dec 16
20°FNov 22Nov 30Dec 4Dec 8Dec 13Dec 18Dec 22Dec 28Jan 4
16°FDec 7Dec 14Dec 22Dec 28Jan 1Jan 4Jan 9Jan 15Jan 25

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°F205198193188183179175170162
32°F228220216213209206201196186
28°F255248242238234229225220214
24°F281273268263258253248243236
20°F311302296291285280274268259
16°F338329323317310305300294284

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
98% 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
4,647
Cooling degree days, base 65°F
1,228
Growing degree days, base 40°F
6,356
Growing degree days, base 45°F
5,019
Growing degree days, base 50°F
3,841
Growing degree days, base 55°F
2,823
Growing degree days, base 60°F
1,954

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January97605
February82506
March677138
April34713165
May12274418
June13241678
July0389854
August1334798
September38155567
October26623243
November551058
December832012

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 26.7 km from Middletown. 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 USW00013781 (Wilmington New Castle CO AP). Public domain.