Rensselaer County climate

Rensselaer County Frost Dates and Growing Season

NOAA 1991-2020 normals for Grafton, 8.8 km from Rensselaer County, elevation 1560 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grafton. 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 1 and the first fall freeze around October 11, a growing season of about 162 days.

Median at 36°F
last May 14, first October 1
Median at 32°F
last May 1, first October 11
Median at 28°F
last April 18, first October 25

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 30May 25May 21May 18May 14May 10May 7May 3Apr 30
32°FMay 15May 10May 6May 3May 1Apr 29Apr 26Apr 23Apr 18
28°FMay 2Apr 28Apr 24Apr 21Apr 18Apr 15Apr 13Apr 9Apr 5
24°FApr 20Apr 16Apr 13Apr 10Apr 7Apr 5Apr 3Apr 1Mar 28
20°FApr 12Apr 6Apr 4Apr 2Mar 31Mar 29Mar 26Mar 21Mar 16
16°FApr 4Apr 1Mar 30Mar 27Mar 23Mar 20Mar 17Mar 13Mar 9

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 19Sep 24Sep 27Sep 29Oct 1Oct 4Oct 6Oct 9Oct 15
32°FSep 28Oct 2Oct 5Oct 8Oct 11Oct 15Oct 19Oct 22Oct 27
28°FOct 7Oct 13Oct 18Oct 22Oct 25Oct 28Oct 31Nov 3Nov 7
24°FOct 23Oct 29Nov 1Nov 2Nov 5Nov 8Nov 11Nov 14Nov 20
20°FNov 2Nov 6Nov 10Nov 13Nov 16Nov 20Nov 23Nov 28Dec 2
16°FNov 12Nov 16Nov 20Nov 24Nov 27Dec 1Dec 2Dec 6Dec 12

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°F157151146142138134131126120
32°F181174169166162158154149142
28°F207201196191187183178172166
24°F230222218214211207204198192
20°F251244239234231227223219212
16°F270262258253248244240235229

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
7,197
Cooling degree days, base 65°F
348
Growing degree days, base 40°F
4,209
Growing degree days, base 45°F
3,155
Growing degree days, base 50°F
2,235
Growing degree days, base 55°F
1,450
Growing degree days, base 60°F
808

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,32802
February1,14800
March1,02505
April604459
May28817219
June9061422
July20127572
August34109541
September18228306
October496192
November819016
December1,16401

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 8.8 km from Rensselaer 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 USC00303360 (Grafton). Public domain.