Marshfield climate

Marshfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Marshfield Exp Farm, 4.4 km from Marshfield, elevation 1237 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Marshfield Exp Farm. 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 5 and the first fall freeze around October 5, a growing season of about 150 days.

Median at 36°F
last May 15, first September 26
Median at 32°F
last May 5, first October 5
Median at 28°F
last April 25, first October 16

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 30May 25May 22May 18May 15May 12May 9May 6May 3
32°FMay 20May 15May 11May 8May 5May 3Apr 30Apr 26Apr 22
28°FMay 10May 4May 1Apr 28Apr 25Apr 22Apr 19Apr 15Apr 10
24°FApr 29Apr 23Apr 19Apr 16Apr 13Apr 9Apr 6Apr 3Mar 30
20°FApr 19Apr 13Apr 9Apr 6Apr 3Apr 1Mar 30Mar 25Mar 19
16°FApr 10Apr 5Apr 2Mar 31Mar 30Mar 25Mar 21Mar 17Mar 12

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 21Sep 24Sep 26Sep 29Oct 1Oct 4Oct 8
32°FSep 22Sep 26Sep 30Oct 2Oct 5Oct 8Oct 10Oct 14Oct 19
28°FOct 1Oct 6Oct 10Oct 13Oct 16Oct 20Oct 22Oct 27Nov 1
24°FOct 13Oct 20Oct 23Oct 27Oct 29Nov 1Nov 4Nov 7Nov 12
20°FOct 27Nov 1Nov 3Nov 6Nov 8Nov 11Nov 14Nov 17Nov 22
16°FNov 3Nov 7Nov 11Nov 14Nov 16Nov 19Nov 22Nov 25Nov 29

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°F150144138135131128123119111
32°F169163157153150147143138132
28°F194187182178173169165160153
24°F218211206202197193188184175
20°F239231227222218215211206198
16°F255249243238234230226221214

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
8,203
Cooling degree days, base 65°F
423
Growing degree days, base 40°F
4,099
Growing degree days, base 45°F
3,118
Growing degree days, base 50°F
2,256
Growing degree days, base 55°F
1,512
Growing degree days, base 60°F
894

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57200
February1,32200
March1,08807
April661139
May30920219
June7489466
July17162609
August37115542
September20435297
October570371
November96505
December1,38600

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 4.4 km from Marshfield. 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 USC00475120 (Marshfield Exp Farm). Public domain.