Norfolk climate

Norfolk Frost Dates and Growing Season

NOAA 1991-2020 normals for Massena Intl AP, 18.9 km from Norfolk, elevation 214 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Massena 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 May 8 and the first fall freeze around October 1, a growing season of about 144 days.

Median at 36°F
last May 19, first September 21
Median at 32°F
last May 8, first October 1
Median at 28°F
last April 28, first October 13

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 2May 30May 26May 22May 19May 17May 14May 10May 6
32°FMay 23May 18May 14May 11May 8May 6May 3Apr 30Apr 27
28°FMay 13May 7May 3Apr 30Apr 28Apr 25Apr 23Apr 19Apr 15
24°FApr 30Apr 25Apr 21Apr 19Apr 17Apr 14Apr 11Apr 8Apr 5
20°FApr 18Apr 14Apr 10Apr 7Apr 5Apr 3Apr 1Mar 31Mar 26
16°FApr 9Apr 5Apr 3Apr 1Mar 31Mar 28Mar 25Mar 21Mar 16

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 8Sep 11Sep 15Sep 18Sep 21Sep 24Sep 27Sep 30Oct 3
32°FSep 17Sep 23Sep 26Sep 29Oct 1Oct 3Oct 6Oct 10Oct 17
28°FSep 30Oct 3Oct 7Oct 10Oct 13Oct 17Oct 20Oct 24Oct 29
24°FOct 8Oct 15Oct 19Oct 22Oct 25Oct 29Nov 1Nov 3Nov 7
20°FOct 21Oct 27Oct 31Nov 2Nov 4Nov 7Nov 10Nov 15Nov 19
16°FNov 3Nov 7Nov 10Nov 13Nov 15Nov 18Nov 22Nov 26Dec 1

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°F141134130126122119114110104
32°F163157151148144141136131125
28°F188182176172168163159154147
24°F211204199195191187182177170
20°F231226221217214210205201196
16°F250243238234230226222218213

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
7,987
Cooling degree days, base 65°F
406
Growing degree days, base 40°F
4,100
Growing degree days, base 45°F
3,103
Growing degree days, base 50°F
2,229
Growing degree days, base 55°F
1,477
Growing degree days, base 60°F
861

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,53000
February1,32300
March1,13304
April663137
May30017215
June8478445
July17157604
August38117544
September19934299
October546273
November87809
December1,27700

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 18.9 km from Norfolk. 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 USW00094725 (Massena Intl AP). Public domain.