Princeton climate

Princeton Frost Dates and Growing Season

NOAA 1991-2020 normals for Princeton 1 W, 2.1 km from Princeton, elevation 480 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Princeton 1 W. 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 13 and the first fall freeze around October 25, a growing season of about 194 days.

Median at 36°F
last April 24, first October 15
Median at 32°F
last April 13, first October 25
Median at 28°F
last April 2, first November 3

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 9May 4May 1Apr 28Apr 24Apr 21Apr 18Apr 15Apr 10
32°FApr 30Apr 24Apr 19Apr 16Apr 13Apr 9Apr 6Apr 2Mar 29
28°FApr 18Apr 11Apr 8Apr 4Apr 2Mar 30Mar 27Mar 22Mar 16
24°FApr 7Apr 2Mar 30Mar 26Mar 22Mar 19Mar 16Mar 12Mar 4
20°FMar 29Mar 23Mar 19Mar 16Mar 13Mar 9Mar 5Mar 1Feb 21
16°FMar 18Mar 13Mar 8Mar 5Mar 2Feb 28Feb 22Feb 16Feb 7

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 1Oct 6Oct 9Oct 12Oct 15Oct 18Oct 20Oct 23Oct 27
32°FOct 10Oct 17Oct 20Oct 23Oct 25Oct 28Oct 30Nov 2Nov 6
28°FOct 20Oct 26Oct 28Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17
24°FOct 29Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 24Dec 1
20°FNov 7Nov 12Nov 16Nov 20Nov 24Nov 28Dec 1Dec 6Dec 12
16°FNov 15Nov 24Nov 28Dec 1Dec 5Dec 9Dec 15Dec 21Dec 26

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°F191186181176173169164159153
32°F214208203198194190185179171
28°F238229224219215212207201192
24°F261251245240235230225220212
20°F284275268263256252247240232
16°F309299292285278273268260252

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
4,920
Cooling degree days, base 65°F
1,303
Growing degree days, base 40°F
6,429
Growing degree days, base 45°F
5,137
Growing degree days, base 50°F
3,980
Growing degree days, base 55°F
2,958
Growing degree days, base 60°F
2,064

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07103
February86208
March664258
April32017203
May100105472
June7283726
July0372837
August2333797
September46160565
October27729252
November633152
December93808

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 2.1 km from Princeton. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00127125 (Princeton 1 W). Public domain.