West Branch climate

West Branch Frost Dates and Growing Season

NOAA 1991-2020 normals for W Branch 3SE, 3.9 km from West Branch, elevation 885 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for W Branch 3SE. 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 15 and the first fall freeze around October 4, a growing season of about 143 days.

Median at 36°F
last May 27, first September 24
Median at 32°F
last May 15, first October 4
Median at 28°F
last May 1, first October 17

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 8Jun 4Jun 1May 30May 27May 24May 21May 17May 11
32°FMay 29May 24May 20May 17May 15May 11May 7May 3Apr 29
28°FMay 17May 13May 8May 4May 1Apr 29Apr 26Apr 23Apr 19
24°FMay 5Apr 30Apr 27Apr 23Apr 20Apr 18Apr 14Apr 11Apr 7
20°FApr 21Apr 17Apr 14Apr 11Apr 8Apr 6Apr 3Apr 1Mar 26
16°FApr 13Apr 7Apr 5Apr 2Apr 1Mar 29Mar 25Mar 21Mar 16

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 11Sep 15Sep 19Sep 22Sep 24Sep 26Sep 29Oct 1Oct 5
32°FSep 21Sep 26Sep 29Oct 1Oct 4Oct 7Oct 9Oct 12Oct 17
28°FOct 1Oct 6Oct 11Oct 14Oct 17Oct 20Oct 23Oct 26Oct 31
24°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 1Nov 3Nov 6Nov 11
20°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 13Nov 16Nov 20Nov 25
16°FNov 7Nov 11Nov 15Nov 18Nov 21Nov 25Nov 29Dec 1Dec 7

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°F14013212812412011611110698
32°F163156151147143139134129123
28°F187179174170166163157152144
24°F211204199195191187182177168
20°F236229224219215211208203196
16°F257250244239235231226222215

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
7,872
Cooling degree days, base 65°F
354
Growing degree days, base 40°F
3,908
Growing degree days, base 45°F
2,933
Growing degree days, base 50°F
2,090
Growing degree days, base 55°F
1,370
Growing degree days, base 60°F
778

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42900
February1,25300
March1,08805
April691132
May34119193
June9774429
July31135569
August5096511
September21128281
October563265
November89305
December1,22600

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 3.9 km from West Branch. 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 USC00208800 (W Branch 3SE). Public domain.