Sylvania climate

Sylvania Frost Dates and Growing Season

NOAA 1991-2020 normals for Valley Head, 18.8 km from Sylvania, elevation 1121 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Valley Head. 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 8 and the first fall freeze around October 29, a growing season of about 202 days.

Median at 36°F
last April 21, first October 21
Median at 32°F
last April 8, first October 29
Median at 28°F
last March 28, first November 8

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 5Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 11Apr 7
32°FApr 24Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 29Mar 22
28°FApr 13Apr 7Apr 3Mar 31Mar 28Mar 24Mar 19Mar 15Mar 5
24°FApr 2Mar 27Mar 22Mar 18Mar 14Mar 8Mar 2Feb 25Feb 19
20°FMar 21Mar 14Mar 9Mar 2Feb 26Feb 21Feb 14Feb 7Jan 29
16°FMar 13Mar 1Feb 22Feb 14Feb 7Feb 2Jan 29Jan 18Jan 7

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 7Oct 12Oct 16Oct 19Oct 21Oct 24Oct 26Oct 30Nov 2
32°FOct 17Oct 21Oct 24Oct 27Oct 29Nov 1Nov 3Nov 6Nov 11
28°FOct 25Oct 30Nov 1Nov 4Nov 8Nov 11Nov 16Nov 21Nov 30
24°FNov 3Nov 8Nov 13Nov 16Nov 21Nov 25Dec 1Dec 4Dec 14
20°FNov 13Nov 19Nov 26Dec 1Dec 5Dec 12Dec 22Dec 30Jan 6
16°FNov 28Dec 5Dec 13Dec 23Dec 30Jan 1Jan 6Jan 14Jan 27

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°F201194189185181177174169163
32°F226217212207202198193188180
28°F253244236230225220215211204
24°F286274267260254248241235224
20°F319306299291283275269260249
16°F356340332325316306300289276

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
93% 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
3,622
Cooling degree days, base 65°F
1,337
Growing degree days, base 40°F
7,194
Growing degree days, base 45°F
5,705
Growing degree days, base 50°F
4,366
Growing degree days, base 55°F
3,192
Growing degree days, base 60°F
2,184

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January797027
February625034
March4703120
April23521262
May72105499
June5258703
July0366831
August1348812
September24195621
October19938322
November483397
December712139

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 18.8 km from Sylvania. 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 USC00018469 (Valley Head). Public domain.