Townsend climate

Townsend Frost Dates and Growing Season

NOAA 1991-2020 normals for Townsend 3SE, 5.7 km from Townsend, elevation 3964 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Townsend 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 19 and the first fall freeze around September 19, a growing season of about 122 days.

Median at 36°F
last June 5, first September 7
Median at 32°F
last May 19, first September 19
Median at 28°F
last May 7, first October 1

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 23Jun 16Jun 11Jun 7Jun 5Jun 2May 30May 27May 22
32°FJun 2May 28May 25May 22May 19May 16May 14May 11May 8
28°FMay 20May 15May 12May 9May 7May 5May 3Apr 30Apr 26
24°FMay 8May 4May 2Apr 29Apr 26Apr 23Apr 20Apr 17Apr 11
20°FApr 30Apr 25Apr 21Apr 16Apr 13Apr 9Apr 5Apr 2Mar 25
16°FApr 20Apr 12Apr 7Apr 3Mar 31Mar 26Mar 22Mar 16Mar 10

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°FAug 25Aug 29Sep 1Sep 4Sep 7Sep 10Sep 13Sep 16Sep 21
32°FSep 5Sep 10Sep 14Sep 17Sep 19Sep 22Sep 25Sep 29Oct 2
28°FSep 17Sep 22Sep 25Sep 28Oct 1Oct 2Oct 5Oct 9Oct 14
24°FSep 27Oct 1Oct 3Oct 6Oct 9Oct 13Oct 16Oct 19Oct 24
20°FOct 3Oct 9Oct 13Oct 17Oct 21Oct 24Oct 28Nov 1Nov 4
16°FOct 13Oct 19Oct 25Oct 28Oct 31Nov 2Nov 5Nov 9Nov 15

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°F113106101969288847870
32°F140134130126122118115110103
28°F161156152148145141137133127
24°F187180175171167163158154149
20°F212205199194189185180173165
16°F238230224219213208203196187

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
7,544
Cooling degree days, base 65°F
253
Growing degree days, base 40°F
3,743
Growing degree days, base 45°F
2,702
Growing degree days, base 50°F
1,839
Growing degree days, base 55°F
1,140
Growing degree days, base 60°F
611

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27700
February1,04701
March88505
April612031
May3693148
June16327317
July39118544
August5692502
September24914236
October614150
November96205
December1,27100

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 5.7 km from Townsend. 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 USC00248324 (Townsend 3SE). Public domain.