Summerlin South climate

Summerlin South Frost Dates and Growing Season

NOAA 1991-2020 normals for Red Rock Canyon - Spg Mt Rch S, 12.9 km from Summerlin South, elevation 3780 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Red Rock Canyon - Spg Mt Rch S. 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 13 and the first fall freeze around November 15, a growing season of about 244 days.

Median at 36°F
last April 6, first November 5
Median at 32°F
last March 13, first November 15
Median at 28°F
last February 21, first November 27

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°FApr 25Apr 20Apr 14Apr 10Apr 6Apr 1Mar 28Mar 20Mar 11
32°FApr 11Apr 4Mar 29Mar 21Mar 13Mar 7Mar 2Feb 27Feb 20
28°FMar 19Mar 8Mar 1Feb 26Feb 21Feb 17Feb 11Feb 5Jan 29
24°FFeb 26Feb 17Feb 10Feb 5Feb 1Jan 26Jan 17Jan 9Dec 28
20°FFeb 9Feb 2Jan 28Jan 18Jan 12Jan 4Dec 30Dec 18Dec 8
16°FJan 30Jan 22Jan 17Jan 13Jan 9Jan 3Dec 29Dec 18Dec 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°FOct 22Oct 27Oct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 19
32°FOct 31Nov 5Nov 9Nov 12Nov 15Nov 18Nov 21Nov 25Nov 30
28°FNov 9Nov 16Nov 19Nov 23Nov 27Dec 1Dec 5Dec 9Dec 15
24°FNov 22Nov 28Dec 2Dec 7Dec 11Dec 16Dec 23Dec 30Jan 10
20°FDec 1Dec 7Dec 13Dec 20Dec 27Jan 1Jan 6Jan 17Jan 31
16°FDec 8Dec 14Dec 21Dec 31Jan 3Jan 8Jan 13Jan 21Jan 28

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°F240230224218213209203196188
32°F275264258251244237229221210
28°F311300292285278271265257246
24°F355342332325319311304295285
20°F365365365365359350339331319
16°F365365365365365365365365354

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
95% of years
20°F or colder
61% of years
16°F or colder
18% 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
3,251
Cooling degree days, base 65°F
2,103
Growing degree days, base 40°F
8,105
Growing degree days, base 45°F
6,524
Growing degree days, base 50°F
5,151
Growing degree days, base 55°F
3,969
Growing degree days, base 60°F
2,958

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January69307
February543029
March3943133
April21826271
May72156550
June7411853
July05891,054
August05611,026
September10299740
October13557394
November457189
December72206

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 12.9 km from Summerlin South. 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 USC00266691 (Red Rock Canyon - Spg Mt Rch S). Public domain.