Delaware County climate

Delaware County Frost Dates and Growing Season

NOAA 1991-2020 normals for Delhi 2 Se, 7.9 km from Delaware County, elevation 1460 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Delhi 2 Se. 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 May 19 and the first fall freeze around October 1, a growing season of about 132 days.

Median at 36°F
last June 2, first September 20
Median at 32°F
last May 19, first October 1
Median at 28°F
last May 5, first October 11

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

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 5Sep 10Sep 14Sep 18Sep 20Sep 23Sep 25Sep 29Oct 3
32°FSep 17Sep 22Sep 25Sep 29Oct 1Oct 3Oct 5Oct 8Oct 14
28°FSep 29Oct 1Oct 5Oct 7Oct 11Oct 15Oct 18Oct 22Oct 28
24°FOct 6Oct 12Oct 17Oct 21Oct 26Oct 30Nov 2Nov 5Nov 10
20°FOct 20Oct 27Nov 1Nov 3Nov 7Nov 10Nov 14Nov 18Nov 23
16°FNov 2Nov 7Nov 11Nov 15Nov 18Nov 21Nov 24Nov 29Dec 4

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°F1291221171131091051009587
32°F154147141136132127123118112
28°F182174169163158154150144136
24°F208200194189185180177169161
20°F233226221215212207203197190
16°F252245240235230227223218211

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
7,449
Cooling degree days, base 65°F
305
Growing degree days, base 40°F
3,980
Growing degree days, base 45°F
2,953
Growing degree days, base 50°F
2,066
Growing degree days, base 55°F
1,316
Growing degree days, base 60°F
719

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,34700
February1,16100
March1,03804
April642248
May33115195
June11759394
July39112538
August5288501
September20229291
October533280
November830014
December1,15801

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 7.9 km from Delaware 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 USC00302036 (Delhi 2 Se). Public domain.