Trenton climate

Trenton Frost Dates and Growing Season

NOAA 1991-2020 normals for Trenton Dam 1N, 4.8 km from Trenton, elevation 2813 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Trenton Dam 1N. 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 29 and the first fall freeze around October 13, a growing season of about 166 days.

Median at 36°F
last May 8, first October 5
Median at 32°F
last April 29, first October 13
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 21May 16May 13May 10May 8May 6May 3May 1Apr 27
32°FMay 12May 8May 5May 2Apr 29Apr 26Apr 23Apr 19Apr 13
28°FMay 2Apr 27Apr 23Apr 20Apr 16Apr 13Apr 10Apr 6Mar 31
24°FApr 22Apr 16Apr 13Apr 9Apr 6Apr 3Mar 31Mar 26Mar 19
20°FApr 14Apr 8Apr 4Apr 1Mar 30Mar 25Mar 20Mar 14Mar 8
16°FApr 4Mar 31Mar 26Mar 21Mar 17Mar 13Mar 8Mar 5Feb 28

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 23Sep 27Sep 30Oct 2Oct 5Oct 7Oct 9Oct 12Oct 16
32°FOct 1Oct 5Oct 8Oct 10Oct 13Oct 15Oct 17Oct 20Oct 24
28°FOct 9Oct 14Oct 17Oct 19Oct 22Oct 24Oct 26Oct 29Nov 2
24°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 3Nov 7Nov 11
20°FOct 23Oct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 21
16°FNov 1Nov 5Nov 9Nov 13Nov 16Nov 19Nov 23Nov 27Dec 2

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°F165159155151147144141137130
32°F186179173170166162158154147
28°F206200195191187183178173167
24°F226219214209204200197192184
20°F246238232228223218213207199
16°F265257252246242237232226217

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
5,843
Cooling degree days, base 65°F
1,123
Growing degree days, base 40°F
5,708
Growing degree days, base 45°F
4,513
Growing degree days, base 50°F
3,461
Growing degree days, base 55°F
2,546
Growing degree days, base 60°F
1,769

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,13800
February94304
March738037
April4484119
May19852337
June26226650
July3378840
August7320778
September88131499
October39411175
November767022
December1,09301

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 4.8 km from Trenton. 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 USC00258628 (Trenton Dam 1N). Public domain.