Herkimer County climate

Herkimer County Frost Dates and Growing Season

NOAA 1991-2020 normals for Trenton Falls, 22.4 km from Herkimer County, elevation 800 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Trenton Falls. 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 13, a growing season of about 161 days.

Median at 36°F
last May 17, first October 1
Median at 32°F
last May 4, first October 13
Median at 28°F
last April 21, first October 28

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 31May 28May 24May 21May 17May 14May 10May 6May 1
32°FMay 23May 16May 11May 7May 4Apr 30Apr 28Apr 24Apr 20
28°FMay 8May 1Apr 28Apr 24Apr 21Apr 18Apr 14Apr 10Apr 5
24°FApr 20Apr 16Apr 13Apr 10Apr 7Apr 5Apr 3Apr 1Mar 29
20°FApr 11Apr 7Apr 5Apr 3Apr 2Mar 31Mar 29Mar 25Mar 20
16°FApr 6Apr 4Apr 1Mar 31Mar 29Mar 25Mar 22Mar 19Mar 15

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 18Sep 22Sep 26Sep 28Oct 1Oct 3Oct 5Oct 9Oct 15
32°FSep 29Oct 2Oct 5Oct 9Oct 13Oct 16Oct 20Oct 23Oct 29
28°FOct 10Oct 17Oct 21Oct 24Oct 28Oct 30Nov 1Nov 4Nov 8
24°FOct 26Oct 30Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 20
20°FNov 2Nov 7Nov 11Nov 13Nov 16Nov 18Nov 22Nov 25Dec 1
16°FNov 11Nov 15Nov 19Nov 22Nov 24Nov 27Dec 1Dec 4Dec 9

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°F156150144140136131126122116
32°F183175170165161156151145138
28°F210203197193188183178173164
24°F228223219215212208204200195
20°F246239235231227224220215211
16°F260253248243240237234229224

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
7,466
Cooling degree days, base 65°F
375
Growing degree days, base 40°F
4,144
Growing degree days, base 45°F
3,121
Growing degree days, base 50°F
2,233
Growing degree days, base 55°F
1,466
Growing degree days, base 60°F
834

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,39800
February1,20200
March1,08806
April634141
May31420223
June9762421
July21142586
August32109542
September18440314
October493288
November821011
December1,18300

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 22.4 km from Herkimer County. 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 USC00308578 (Trenton Falls). Public domain.