Franklin climate

Franklin Frost Dates and Growing Season

NOAA 1991-2020 normals for West Medway, 6.3 km from Franklin, elevation 210 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for West Medway. 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 162 days.

Median at 36°F
last May 11, first October 1
Median at 32°F
last April 30, first October 9
Median at 28°F
last April 16, first October 22

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 17May 14May 11May 7May 5May 2Apr 28
32°FMay 14May 8May 4May 2Apr 30Apr 27Apr 24Apr 21Apr 17
28°FMay 1Apr 25Apr 21Apr 18Apr 16Apr 12Apr 8Apr 5Apr 2
24°FApr 16Apr 10Apr 6Apr 4Apr 2Mar 31Mar 29Mar 25Mar 20
20°FApr 3Mar 31Mar 28Mar 25Mar 23Mar 19Mar 17Mar 14Mar 9
16°FMar 27Mar 23Mar 19Mar 16Mar 14Mar 11Mar 9Mar 5Mar 1

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 20Sep 23Sep 26Sep 29Oct 1Oct 3Oct 5Oct 8Oct 12
32°FSep 29Oct 1Oct 4Oct 7Oct 9Oct 12Oct 15Oct 18Oct 23
28°FOct 7Oct 11Oct 15Oct 19Oct 22Oct 25Oct 28Nov 1Nov 5
24°FOct 18Oct 24Oct 29Nov 1Nov 3Nov 6Nov 9Nov 14Nov 20
20°FNov 1Nov 6Nov 9Nov 13Nov 17Nov 21Nov 25Dec 1Dec 5
16°FNov 15Nov 21Nov 25Nov 29Dec 1Dec 4Dec 7Dec 13Dec 19

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°F159152148145141138133128122
32°F179174169165162158154150143
28°F209201196191187182178173166
24°F237229224219214211206200194
20°F264255248244240235231225218
16°F283275270266261256251247239

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
6,066
Cooling degree days, base 65°F
665
Growing degree days, base 40°F
4,937
Growing degree days, base 45°F
3,780
Growing degree days, base 50°F
2,782
Growing degree days, base 55°F
1,932
Growing degree days, base 60°F
1,227

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,16702
February99700
March87107
April521266
May23526269
June55122518
July5242702
August11201655
September11368408
October4114126
November690026
December99003

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 6.3 km from Franklin. 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 USC00199316 (West Medway). Public domain.