Moapa Valley climate

Moapa Valley Frost Dates and Growing Season

NOAA 1991-2020 normals for Overton, 3.5 km from Moapa Valley, elevation 1250 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Overton. 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 February 26 and the first fall freeze around November 22, a growing season of about 268 days.

Median at 36°F
last March 15, first November 12
Median at 32°F
last February 26, first November 22
Median at 28°F
last February 5, first December 2

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 11Apr 4Mar 30Mar 21Mar 15Mar 11Mar 7Mar 3Feb 26
32°FMar 16Mar 8Mar 3Feb 28Feb 26Feb 21Feb 17Feb 10Feb 4
28°FFeb 28Feb 21Feb 16Feb 10Feb 5Feb 1Jan 27Jan 20Jan 11
24°FFeb 10Feb 1Jan 27Jan 21Jan 15Jan 9Jan 3Dec 29Dec 22
20°FJan 29Jan 17Jan 9Jan 5Jan 2Dec 30Dec 26Dec 22Dec 12
16°F–––––––––

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 31Nov 4Nov 7Nov 9Nov 12Nov 14Nov 16Nov 20Nov 24
32°FNov 9Nov 13Nov 16Nov 19Nov 22Nov 24Nov 27Dec 1Dec 6
28°FNov 18Nov 23Nov 26Nov 30Dec 2Dec 6Dec 9Dec 15Dec 23
24°FNov 28Dec 3Dec 6Dec 11Dec 16Dec 21Dec 26Jan 1Jan 9
20°FDec 6Dec 12Dec 17Dec 23Dec 26Dec 30Jan 2Jan 6Jan 13
16°F–––––––––

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°F262255250244238233226218210
32°F292285279273268263258251242
28°F330321313305299293288282273
24°F365354347342336331325317307
20°F365365365365365364357349339
16°F365365365365365365365365365

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
88% of years
20°F or colder
41% of years
16°F or colder
9% 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
2,067
Cooling degree days, base 65°F
3,443
Growing degree days, base 40°F
10,517
Growing degree days, base 45°F
8,765
Growing degree days, base 50°F
7,159
Growing degree days, base 55°F
5,748
Growing degree days, base 60°F
4,518

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January536033
February3590101
March18822304
April63113500
May8356812
June16261,076
July08381,303
August07861,251
September1527976
October42167591
November2959189
December575023

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 3.5 km from Moapa Valley. 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 USC00265846 (Overton). Public domain.