Rumney climate

Rumney Frost Dates and Growing Season

NOAA 1991-2020 normals for Wentworth, 10.8 km from Rumney, elevation 653 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wentworth. 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 12 and the first fall freeze around October 6, a growing season of about 146 days.

Median at 36°F
last May 25, first September 26
Median at 32°F
last May 12, first October 6
Median at 28°F
last April 30, first October 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°FJun 9Jun 4Jun 1May 29May 25May 22May 19May 16May 11
32°FMay 25May 21May 18May 15May 12May 9May 7May 3Apr 30
28°FMay 12May 8May 4May 2Apr 30Apr 27Apr 25Apr 22Apr 18
24°FApr 28Apr 24Apr 21Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4
20°FApr 18Apr 13Apr 9Apr 7Apr 4Apr 3Apr 1Mar 30Mar 23
16°FApr 8Apr 4Apr 2Apr 1Mar 30Mar 27Mar 23Mar 19Mar 15

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 12Sep 17Sep 20Sep 23Sep 26Sep 29Oct 1Oct 3Oct 8
32°FSep 23Sep 28Oct 1Oct 3Oct 6Oct 8Oct 12Oct 16Oct 22
28°FOct 5Oct 9Oct 13Oct 17Oct 20Oct 23Oct 27Oct 31Nov 4
24°FOct 16Oct 21Oct 26Oct 30Nov 1Nov 4Nov 7Nov 11Nov 15
20°FOct 30Nov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 22Nov 26
16°FNov 8Nov 13Nov 16Nov 20Nov 23Nov 25Nov 29Dec 1Dec 6

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°F141133129126122118114109101
32°F166160154150146142138133126
28°F192186181176172169164158151
24°F216211206202198195190185177
20°F239232228223220216212208202
16°F256249244241238234230226219

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
7,847
Cooling degree days, base 65°F
333
Growing degree days, base 40°F
3,895
Growing degree days, base 45°F
2,914
Growing degree days, base 50°F
2,062
Growing degree days, base 55°F
1,344
Growing degree days, base 60°F
761

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,45000
February1,24400
March1,09106
April683026
May3417171
June10856400
July21133576
August3897524
September20740297
October561159
November87605
December1,22800

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 10.8 km from Rumney. 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 USC00279091 (Wentworth). Public domain.