Delevan climate

Delevan Frost Dates and Growing Season

NOAA 1991-2020 normals for Franklinville, 17.8 km from Delevan, elevation 1590 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Franklinville. 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 14 and the first fall freeze around October 6, a growing season of about 144 days.

Median at 36°F
last May 27, first September 26
Median at 32°F
last May 14, first October 6
Median at 28°F
last May 2, first October 19

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 10Jun 4Jun 1May 30May 27May 25May 21May 17May 10
32°FMay 30May 26May 22May 18May 14May 10May 7May 3Apr 28
28°FMay 19May 13May 9May 5May 2Apr 30Apr 27Apr 24Apr 19
24°FMay 6May 1Apr 27Apr 24Apr 21Apr 18Apr 15Apr 11Apr 6
20°FApr 22Apr 17Apr 14Apr 11Apr 8Apr 5Apr 3Apr 1Mar 27
16°FApr 11Apr 7Apr 4Apr 2Mar 31Mar 29Mar 26Mar 22Mar 17

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 12Sep 17Sep 21Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7
32°FSep 23Sep 29Oct 1Oct 4Oct 6Oct 9Oct 12Oct 16Oct 20
28°FOct 4Oct 9Oct 12Oct 16Oct 19Oct 22Oct 26Oct 30Nov 4
24°FOct 16Oct 22Oct 27Oct 31Nov 2Nov 5Nov 8Nov 12Nov 17
20°FNov 1Nov 4Nov 7Nov 11Nov 13Nov 16Nov 19Nov 23Nov 28
16°FNov 8Nov 13Nov 16Nov 19Nov 23Nov 26Nov 30Dec 2Dec 8

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°F14113412912412011611210699
32°F165158152148144139135130122
28°F189182177173169164159154147
24°F215209203197194189185179172
20°F238232227223219215210205196
16°F258251247242237233229224217

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
7,386
Cooling degree days, base 65°F
329
Growing degree days, base 40°F
4,066
Growing degree days, base 45°F
3,026
Growing degree days, base 50°F
2,129
Growing degree days, base 55°F
1,370
Growing degree days, base 60°F
759

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33001
February1,17501
March1,05907
April650145
May33120205
June10665412
July37119547
August5191505
September19132301
October513388
November816013
December1,13002

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 17.8 km from Delevan. 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 USC00303025 (Franklinville). Public domain.