Cambridge climate

Cambridge Frost Dates and Growing Season

NOAA 1991-2020 normals for Geneseo, 16.8 km from Cambridge, elevation 639 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Geneseo. 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 20 and the first fall freeze around October 20, a growing season of about 180 days.

Median at 36°F
last May 1, first October 9
Median at 32°F
last April 20, first October 20
Median at 28°F
last April 9, first October 30

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 14May 10May 6May 4May 1Apr 28Apr 25Apr 22Apr 17
32°FMay 6May 1Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10Apr 6
28°FApr 25Apr 19Apr 15Apr 12Apr 9Apr 6Apr 3Mar 31Mar 25
24°FApr 12Apr 7Apr 4Apr 1Mar 30Mar 27Mar 23Mar 19Mar 14
20°FApr 3Mar 30Mar 26Mar 22Mar 19Mar 16Mar 12Mar 9Mar 4
16°FMar 26Mar 21Mar 17Mar 14Mar 11Mar 8Mar 5Mar 2Feb 25

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 25Sep 30Oct 4Oct 7Oct 9Oct 12Oct 15Oct 18Oct 22
32°FOct 5Oct 11Oct 15Oct 18Oct 20Oct 22Oct 24Oct 27Oct 31
28°FOct 17Oct 22Oct 25Oct 28Oct 30Nov 1Nov 3Nov 7Nov 11
24°FOct 30Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 24
20°FNov 4Nov 9Nov 12Nov 16Nov 19Nov 22Nov 25Nov 29Dec 3
16°FNov 11Nov 16Nov 20Nov 24Nov 27Nov 30Dec 2Dec 6Dec 13

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°F179172168164160155151146139
32°F199192187184180177173168161
28°F221214209205202198194189182
24°F244237232226222219214210203
20°F265258252248244239235230222
16°F282275270265261257252247239

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
6,139
Cooling degree days, base 65°F
1,031
Growing degree days, base 40°F
5,630
Growing degree days, base 45°F
4,469
Growing degree days, base 50°F
3,426
Growing degree days, base 55°F
2,502
Growing degree days, base 60°F
1,703

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,31100
February1,06002
March805234
April42810131
May15279399
June16231664
July2324787
August5258718
September87111477
October37517181
November758130
December1,14103

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 16.8 km from Cambridge. 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 USC00113384 (Geneseo). Public domain.