Smithfield climate

Smithfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Newport News Intl AP, 20.7 km from Smithfield, elevation 42 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Newport News Intl 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 1 and the first fall freeze around November 9, a growing season of about 221 days.

Median at 36°F
last April 15, first October 31
Median at 32°F
last April 1, first November 9
Median at 28°F
last March 20, first November 20

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 3Apr 27Apr 22Apr 18Apr 15Apr 12Apr 8Apr 4Mar 31
32°FApr 18Apr 11Apr 7Apr 4Apr 1Mar 29Mar 27Mar 23Mar 18
28°FApr 4Mar 31Mar 27Mar 23Mar 20Mar 17Mar 14Mar 9Mar 2
24°FMar 25Mar 19Mar 14Mar 11Mar 6Mar 2Feb 27Feb 21Feb 13
20°FMar 12Mar 5Mar 1Feb 25Feb 19Feb 13Feb 7Feb 1Jan 23
16°FFeb 28Feb 20Feb 12Feb 5Jan 31Jan 28Jan 22Jan 15Jan 3

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 20Oct 24Oct 26Oct 29Oct 31Nov 1Nov 4Nov 6Nov 11
32°FOct 31Nov 2Nov 4Nov 6Nov 9Nov 11Nov 14Nov 18Nov 25
28°FNov 5Nov 10Nov 13Nov 17Nov 20Nov 24Nov 28Dec 2Dec 8
24°FNov 15Nov 22Nov 27Dec 1Dec 4Dec 9Dec 16Dec 24Jan 1
20°FDec 1Dec 7Dec 14Dec 20Dec 26Jan 1Jan 4Jan 11Jan 21
16°FDec 14Dec 24Dec 30Jan 2Jan 7Jan 12Jan 18Jan 26Feb 2

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°F217210206201198194189185178
32°F241234229225221216212208203
28°F270261254249244240235230222
24°F304293286279273268263256248
20°F335328318311306300293286275
16°F365360351342334329321311303

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
99% of years
16°F or colder
83% 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
3,536
Cooling degree days, base 65°F
1,562
Growing degree days, base 40°F
7,456
Growing degree days, base 45°F
5,961
Growing degree days, base 50°F
4,627
Growing degree days, base 55°F
3,448
Growing degree days, base 60°F
2,427

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January781029
February641136
March5155103
April23840277
May72123516
June6294738
July0442907
August0383848
September12215652
October16854360
November4334114
December671147

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 20.7 km from Smithfield. 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 USW00093741 (Newport News Intl AP). Public domain.