Princeton climate

Princeton Frost Dates and Growing Season

NOAA 1991-2020 normals for Grand Lake Stream, 16.6 km from Princeton, elevation 290 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grand Lake Stream. 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 4 and the first fall freeze around October 10, a growing season of about 157 days.

Median at 36°F
last May 17, first October 1
Median at 32°F
last May 4, first October 10
Median at 28°F
last April 24, first October 24

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°FJun 1May 28May 24May 21May 17May 13May 10May 7May 3
32°FMay 18May 13May 9May 7May 4May 2Apr 30Apr 28Apr 24
28°FMay 6May 1Apr 29Apr 26Apr 24Apr 21Apr 18Apr 15Apr 10
24°FApr 23Apr 19Apr 16Apr 12Apr 10Apr 7Apr 5Apr 3Mar 31
20°FApr 13Apr 9Apr 6Apr 4Apr 2Apr 1Mar 29Mar 24Mar 18
16°FApr 6Apr 3Mar 31Mar 30Mar 26Mar 22Mar 19Mar 15Mar 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°FSep 20Sep 24Sep 27Sep 30Oct 1Oct 3Oct 5Oct 7Oct 11
32°FOct 1Oct 3Oct 6Oct 8Oct 10Oct 13Oct 15Oct 19Oct 23
28°FOct 9Oct 14Oct 17Oct 20Oct 24Oct 26Oct 29Nov 2Nov 6
24°FOct 24Oct 28Nov 1Nov 2Nov 5Nov 8Nov 11Nov 14Nov 19
20°FNov 3Nov 8Nov 11Nov 14Nov 17Nov 19Nov 23Nov 26Nov 30
16°FNov 15Nov 19Nov 23Nov 26Nov 28Nov 30Dec 2Dec 5Dec 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°F153148144139135132128123117
32°F175169164161157154150146139
28°F201195191186182179174169163
24°F224218214211208204201196191
20°F247241236233229225221215209
16°F266259254249245242238233226

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
7,915
Cooling degree days, base 65°F
298
Growing degree days, base 40°F
3,789
Growing degree days, base 45°F
2,808
Growing degree days, base 50°F
1,963
Growing degree days, base 55°F
1,254
Growing degree days, base 60°F
692

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,45700
February1,25600
March1,10102
April714014
May3806141
June12741367
July31123556
August38100527
September19527290
October548160
November85406
December1,21500

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 16.6 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 USC00173261 (Grand Lake Stream). Public domain.