Nitro climate

Nitro Frost Dates and Growing Season

NOAA 1991-2020 normals for Winfield Locks, 14 km from Nitro, elevation 621 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Winfield Locks. 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 18 and the first fall freeze around October 30, a growing season of about 193 days.

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

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 11Oct 14Oct 17Oct 20Oct 22Oct 24Oct 27Oct 31
32°FOct 17Oct 22Oct 25Oct 28Oct 30Nov 1Nov 3Nov 5Nov 10
28°FOct 29Nov 1Nov 3Nov 5Nov 8Nov 11Nov 14Nov 17Nov 23
24°FNov 5Nov 10Nov 13Nov 16Nov 20Nov 24Nov 28Dec 1Dec 8
20°FNov 14Nov 20Nov 26Nov 29Dec 2Dec 7Dec 11Dec 19Dec 26
16°FNov 26Dec 2Dec 8Dec 14Dec 19Dec 25Dec 31Jan 4Jan 13

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°F191184179175170166161156148
32°F214207202198193189183176168
28°F239231226222218214210205197
24°F272261254248243238232227221
20°F298289282275268262256250240
16°F326315306302297291283276266

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
4,568
Cooling degree days, base 65°F
1,154
Growing degree days, base 40°F
6,407
Growing degree days, base 45°F
5,052
Growing degree days, base 50°F
3,855
Growing degree days, base 55°F
2,807
Growing degree days, base 60°F
1,907

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January967010
February790013
March644260
April30918214
May11984433
June13226663
July1335800
August1308772
September43154561
October27225249
November571164
December839017

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 14 km from Nitro. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00469683 (Winfield Locks). Public domain.