Oxford County climate

Oxford County Frost Dates and Growing Season

NOAA 1991-2020 normals for Rumford 6SW, 8 km from Oxford County, elevation 630 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rumford 6SW. 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 September 29, a growing season of about 139 days.

Median at 36°F
last May 24, first September 18
Median at 32°F
last May 12, first September 29
Median at 28°F
last April 30, first October 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°FJun 6Jun 2May 30May 27May 24May 21May 18May 15May 10
32°FMay 27May 22May 18May 15May 12May 9May 7May 4Apr 30
28°FMay 12May 8May 5May 2Apr 30Apr 29Apr 26Apr 23Apr 19
24°FApr 30Apr 26Apr 23Apr 21Apr 18Apr 16Apr 13Apr 9Apr 6
20°FApr 20Apr 16Apr 12Apr 9Apr 7Apr 5Apr 3Apr 1Mar 28
16°FApr 10Apr 6Apr 4Apr 2Apr 1Mar 30Mar 27Mar 22Mar 18

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 7Sep 10Sep 13Sep 16Sep 18Sep 21Sep 23Sep 26Oct 1
32°FSep 15Sep 19Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7Oct 11
28°FSep 28Oct 1Oct 3Oct 6Oct 8Oct 11Oct 16Oct 21Oct 29
24°FOct 6Oct 11Oct 16Oct 20Oct 24Oct 27Nov 1Nov 4Nov 10
20°FOct 22Oct 27Nov 1Nov 3Nov 6Nov 10Nov 13Nov 17Nov 21
16°FNov 3Nov 9Nov 13Nov 16Nov 18Nov 21Nov 24Nov 27Dec 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°F13412912512111811411010599
32°F158150147143139134130126119
28°F182175170165162158154149143
24°F208201196192187184179174166
20°F229224219215212208204199193
16°F251243239235232228224220214

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
8,287
Cooling degree days, base 65°F
264
Growing degree days, base 40°F
3,657
Growing degree days, base 45°F
2,708
Growing degree days, base 50°F
1,890
Growing degree days, base 55°F
1,200
Growing degree days, base 60°F
650

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,50000
February1,30700
March1,17004
April728021
May3837147
June12450380
July33105538
August4873490
September23728261
October591146
November90004
December1,26600

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 8 km from Oxford County. 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 USC00177336 (Rumford 6SW). Public domain.