Tiverton climate

Tiverton Frost Dates and Growing Season

NOAA 1991-2020 normals for Tiverton, 0.3 km from Tiverton, elevation 90 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tiverton. 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 11 and the first fall freeze around November 2, a growing season of about 203 days.

Median at 36°F
last April 26, first October 21
Median at 32°F
last April 11, first November 2
Median at 28°F
last March 31, first November 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°FMay 7May 3May 1Apr 29Apr 26Apr 23Apr 22Apr 19Apr 15
32°FApr 22Apr 19Apr 16Apr 13Apr 11Apr 9Apr 6Apr 4Apr 1
28°FApr 11Apr 7Apr 5Apr 2Mar 31Mar 30Mar 27Mar 23Mar 19
24°FApr 3Mar 30Mar 27Mar 23Mar 21Mar 18Mar 16Mar 12Mar 7
20°FMar 27Mar 22Mar 18Mar 15Mar 12Mar 9Mar 6Mar 3Feb 26
16°FMar 20Mar 13Mar 9Mar 6Mar 3Feb 28Feb 23Feb 18Feb 11

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 8Oct 13Oct 16Oct 19Oct 21Oct 24Oct 27Oct 30Nov 3
32°FOct 20Oct 26Oct 29Nov 1Nov 2Nov 5Nov 8Nov 11Nov 15
28°FNov 2Nov 5Nov 8Nov 11Nov 13Nov 16Nov 19Nov 23Nov 30
24°FNov 10Nov 14Nov 18Nov 21Nov 25Nov 29Dec 1Dec 5Dec 12
20°FNov 22Nov 27Dec 1Dec 4Dec 7Dec 11Dec 15Dec 20Dec 26
16°FDec 4Dec 11Dec 16Dec 20Dec 23Dec 27Jan 1Jan 5Jan 11

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°F195189185181178174170166160
32°F220214210207203200196192186
28°F247240236231227223220215210
24°F272264258253248244240236229
20°F295288282277272267262256249
16°F318309304299295290285279270

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
5,268
Cooling degree days, base 65°F
880
Growing degree days, base 40°F
5,584
Growing degree days, base 45°F
4,321
Growing degree days, base 50°F
3,226
Growing degree days, base 55°F
2,295
Growing degree days, base 60°F
1,515

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,05201
February89901
March78609
April462274
May19223300
June29145566
July1309773
August1280744
September48111513
October30610200
November605038
December88707

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 0.3 km from Tiverton. 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 USC00377581 (Tiverton). Public domain.