Strafford climate

Strafford Frost Dates and Growing Season

NOAA 1991-2020 normals for Rochester Skyhaven AP, 21.9 km from Strafford, elevation 323 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rochester Skyhaven 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 30 and the first fall freeze around October 9, a growing season of about 161 days.

Median at 36°F
last May 12, first September 30
Median at 32°F
last April 30, first October 9
Median at 28°F
last April 17, first October 23

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 25May 20May 18May 14May 12May 9May 6May 4May 1
32°FMay 13May 8May 5May 2Apr 30Apr 28Apr 26Apr 22Apr 18
28°FApr 29Apr 25Apr 22Apr 19Apr 17Apr 14Apr 10Apr 8Apr 4
24°FApr 17Apr 12Apr 9Apr 6Apr 4Apr 3Apr 1Mar 30Mar 23
20°FApr 6Apr 3Mar 31Mar 30Mar 27Mar 23Mar 20Mar 17Mar 13
16°FMar 31Mar 28Mar 24Mar 21Mar 18Mar 15Mar 13Mar 10Mar 6

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 17Sep 21Sep 24Sep 27Sep 30Oct 1Oct 4Oct 6Oct 12
32°FSep 27Oct 1Oct 4Oct 6Oct 9Oct 12Oct 15Oct 18Oct 25
28°FOct 7Oct 12Oct 16Oct 20Oct 23Oct 26Oct 30Nov 2Nov 7
24°FOct 21Oct 26Oct 30Nov 2Nov 5Nov 9Nov 12Nov 16Nov 21
20°FNov 4Nov 9Nov 13Nov 17Nov 20Nov 22Nov 26Nov 30Dec 4
16°FNov 15Nov 21Nov 25Nov 28Dec 1Dec 2Dec 5Dec 10Dec 16

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°F155149145141138134131126120
32°F181175170165161157153148142
28°F208202196192188184180175168
24°F233226221217213209205200194
20°F256250245241237233228222216
16°F275269264260256253249245239

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
6,790
Cooling degree days, base 65°F
506
Growing degree days, base 40°F
4,453
Growing degree days, base 45°F
3,372
Growing degree days, base 50°F
2,438
Growing degree days, base 55°F
1,651
Growing degree days, base 60°F
1,001

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27100
February1,08600
March95807
April582354
May29418213
June7492469
July12190643
August21152597
September15548348
October472394
November770013
December1,09601

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 21.9 km from Strafford. 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 USW00054791 (Rochester Skyhaven AP). Public domain.