Springdale climate

Springdale Frost Dates and Growing Season

NOAA 1991-2020 normals for Zion Np, 2.7 km from Springdale, elevation 4038 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Zion Np. 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 April 13 and the first fall freeze around November 2, a growing season of about 202 days.

Median at 36°F
last April 26, first October 24
Median at 32°F
last April 13, first November 2
Median at 28°F
last March 23, first November 12

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°FMay 14May 7May 2Apr 29Apr 26Apr 23Apr 20Apr 15Apr 9
32°FMay 2Apr 26Apr 21Apr 17Apr 13Apr 8Apr 4Mar 31Mar 22
28°FApr 15Apr 7Apr 2Mar 29Mar 23Mar 17Mar 13Mar 5Feb 26
24°FMar 27Mar 15Mar 9Mar 3Feb 28Feb 23Feb 18Feb 10Feb 1
20°FMar 3Feb 25Feb 18Feb 12Feb 7Feb 2Jan 27Jan 18Jan 5
16°FFeb 15Feb 6Feb 1Jan 25Jan 16Jan 9Jan 3Dec 28Dec 16

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 9Oct 14Oct 18Oct 22Oct 24Oct 27Oct 30Nov 2Nov 7
32°FOct 20Oct 24Oct 28Oct 30Nov 2Nov 5Nov 8Nov 12Nov 17
28°FOct 27Nov 1Nov 5Nov 8Nov 12Nov 15Nov 18Nov 22Nov 26
24°FNov 5Nov 11Nov 15Nov 19Nov 22Nov 25Nov 29Dec 2Dec 8
20°FNov 15Nov 20Nov 25Nov 28Dec 1Dec 5Dec 8Dec 13Dec 20
16°FNov 24Nov 29Dec 3Dec 7Dec 11Dec 16Dec 22Dec 29Jan 9

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°F201193188183178174170163155
32°F226218211206202197192186177
28°F264251243237231224219212203
24°F295286278271266260254245233
20°F330320310303296290284277265
16°F362350342334329323314306292

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
99% of years
16°F or colder
92% 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
3,257
Cooling degree days, base 65°F
2,211
Growing degree days, base 40°F
8,257
Growing degree days, base 45°F
6,699
Growing degree days, base 50°F
5,324
Growing degree days, base 55°F
4,132
Growing degree days, base 60°F
3,097

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January710010
February543032
March3933140
April22024274
May67160560
June5417862
July06171,082
August05691,034
September9339780
October12779426
November4364116
December74709

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 2.7 km from Springdale. 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 USC00429717 (Zion Np). Public domain.