James Town climate

James Town Frost Dates and Growing Season

NOAA 1991-2020 normals for Green Rvr, 5.8 km from James Town, elevation 6160 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Green Rvr. 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 24 and the first fall freeze around September 22, a growing season of about 120 days.

Median at 36°F
last June 7, first September 13
Median at 32°F
last May 24, first September 22
Median at 28°F
last May 9, first October 3

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 21Jun 17Jun 13Jun 10Jun 7Jun 4Jun 1May 29May 22
32°FJun 10Jun 4May 31May 28May 24May 21May 17May 12May 7
28°FMay 28May 21May 17May 13May 9May 6May 3Apr 30Apr 25
24°FMay 16May 9May 4Apr 30Apr 27Apr 24Apr 20Apr 16Apr 11
20°FMay 2Apr 25Apr 20Apr 16Apr 12Apr 8Apr 4Mar 31Mar 25
16°FApr 15Apr 8Apr 4Mar 31Mar 27Mar 21Mar 16Mar 11Mar 6

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 1Sep 5Sep 7Sep 10Sep 13Sep 15Sep 18Sep 21Sep 25
32°FSep 7Sep 13Sep 17Sep 20Sep 22Sep 25Sep 28Oct 1Oct 6
28°FSep 18Sep 24Sep 27Sep 30Oct 3Oct 6Oct 10Oct 14Oct 18
24°FSep 28Oct 3Oct 8Oct 13Oct 16Oct 19Oct 22Oct 24Oct 28
20°FOct 10Oct 16Oct 20Oct 23Oct 26Oct 28Oct 31Nov 3Nov 7
16°FOct 21Oct 25Oct 28Nov 1Nov 2Nov 5Nov 8Nov 11Nov 16

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°F1191101041009693898478
32°F14313613012512011611110699
28°F168160155150146141135129121
24°F191184178174169165160155146
20°F220212206201197193188181173
16°F245237232227222217212206198

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
7,939
Cooling degree days, base 65°F
350
Growing degree days, base 40°F
3,794
Growing degree days, base 45°F
2,823
Growing degree days, base 50°F
1,997
Growing degree days, base 55°F
1,309
Growing degree days, base 60°F
755

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40900
February1,13400
March93601
April665019
May4082134
June14044361
July23170612
August32120553
September21413268
October605048
November1,00701
December1,36700

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 5.8 km from James Town. 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 USC00484065 (Green Rvr). Public domain.