Three Rivers climate

Three Rivers Frost Dates and Growing Season

NOAA 1991-2020 normals for Three Rivers Edison Ph 1, 4.7 km from Three Rivers, elevation 1140 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Three Rivers Edison Ph 1. 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 March 16 and the first fall freeze around November 26, a growing season of about 249 days.

Median at 36°F
last April 13, first November 10
Median at 32°F
last March 16, first November 26
Median at 28°F
last January 30, first December 11

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 4Apr 27Apr 21Apr 17Apr 13Apr 9Apr 5Mar 31Mar 21
32°FApr 14Apr 7Apr 1Mar 25Mar 16Mar 9Feb 28Feb 19Feb 5
28°FMar 18Feb 28Feb 15Feb 6Jan 30Jan 23Jan 14Jan 3Dec 24
24°FFeb 7Jan 28Jan 19Jan 11Jan 3Dec 31Dec 24Dec 19Dec 9
20°F–––––––––
16°F–––––––––

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 21Oct 29Nov 3Nov 7Nov 10Nov 14Nov 17Nov 20Nov 25
32°FNov 5Nov 13Nov 18Nov 23Nov 26Nov 29Dec 2Dec 6Dec 12
28°FNov 22Nov 28Dec 2Dec 7Dec 11Dec 16Dec 20Dec 26Jan 11
24°FDec 1Dec 9Dec 14Dec 19Dec 26Jan 1Jan 6Jan 16Jan 30
20°F–––––––––
16°F–––––––––

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°F236227220215209204198190180
32°F294279269258249242235226216
28°F353343333325317307298283265
24°F365365365365365364356345333
20°F365365365365365365365365365
16°F365365365365365365365365365

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
96% of years
24°F or colder
43% of years
20°F or colder
4% of years
16°F or colder
0% 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
2,643
Cooling degree days, base 65°F
1,774
Growing degree days, base 40°F
8,271
Growing degree days, base 45°F
6,539
Growing degree days, base 50°F
4,996
Growing degree days, base 55°F
3,700
Growing degree days, base 60°F
2,638

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January558026
February420061
March3381157
April21215264
May71110504
June9301743
July0502967
August0470935
September5302747
October9772441
November3611129
December573023

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 4.7 km from Three Rivers. 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 USC00048917 (Three Rivers Edison Ph 1). Public domain.