Fall River County climate

Fall River County Frost Dates and Growing Season

NOAA 1991-2020 normals for Hot Springs, 22.5 km from Fall River County, elevation 3560 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hot Springs. 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 16 and the first fall freeze around September 27, a growing season of about 133 days.

Median at 36°F
last May 29, first September 19
Median at 32°F
last May 16, first September 27
Median at 28°F
last May 5, first October 7

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 12Jun 6Jun 2May 31May 29May 26May 23May 20May 16
32°FMay 31May 26May 22May 19May 16May 13May 10May 8May 4
28°FMay 18May 13May 10May 8May 5May 2Apr 30Apr 28Apr 24
24°FMay 7May 3Apr 30Apr 28Apr 25Apr 22Apr 19Apr 15Apr 10
20°FApr 28Apr 24Apr 20Apr 17Apr 14Apr 11Apr 8Apr 4Mar 29
16°FApr 20Apr 14Apr 10Apr 5Apr 2Mar 31Mar 26Mar 21Mar 13

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 3Sep 8Sep 12Sep 15Sep 19Sep 21Sep 23Sep 26Sep 30
32°FSep 12Sep 18Sep 22Sep 25Sep 27Sep 30Oct 2Oct 5Oct 9
28°FSep 23Sep 28Oct 1Oct 4Oct 7Oct 10Oct 14Oct 17Oct 20
24°FOct 2Oct 9Oct 12Oct 15Oct 18Oct 20Oct 23Oct 26Oct 30
20°FOct 14Oct 18Oct 22Oct 25Oct 27Oct 30Nov 1Nov 5Nov 10
16°FOct 19Oct 25Oct 29Nov 1Nov 4Nov 7Nov 10Nov 15Nov 20

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°F1311251201161121081049892
32°F150145140136133130126121113
28°F171165160156152149145140135
24°F193186181177174169165160154
20°F219210204200195191186181173
16°F243231225219214210205199190

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
6,583
Cooling degree days, base 65°F
644
Growing degree days, base 40°F
4,718
Growing degree days, base 45°F
3,598
Growing degree days, base 50°F
2,643
Growing degree days, base 55°F
1,833
Growing degree days, base 60°F
1,167

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,17000
February99802
March811020
April559159
May30014221
June7495473
July9255711
August17213660
September13864386
October4982102
November852010
December1,15800

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 22.5 km from Fall River 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 USC00394007 (Hot Springs). Public domain.