Black Rock climate

Black Rock Frost Dates and Growing Season

NOAA 1991-2020 normals for Zuni, 4.8 km from Black Rock, elevation 6311 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Zuni. 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 29 and the first fall freeze around October 2, a growing season of about 127 days.

Median at 36°F
last June 6, first September 25
Median at 32°F
last May 29, first October 2
Median at 28°F
last May 12, first October 10

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 21Jun 16Jun 12Jun 9Jun 6Jun 4Jun 2May 31May 24
32°FJun 13Jun 6Jun 3Jun 1May 29May 24May 19May 14May 9
28°FJun 4May 28May 21May 16May 12May 8May 4Apr 30Apr 26
24°FMay 25May 12May 6May 2Apr 29Apr 26Apr 22Apr 18Apr 14
20°FMay 4Apr 29Apr 24Apr 20Apr 16Apr 11Apr 8Apr 3Mar 29
16°FApr 22Apr 14Apr 8Apr 2Mar 29Mar 24Mar 18Mar 13Mar 6

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 12Sep 17Sep 20Sep 23Sep 25Sep 28Sep 30Oct 2Oct 5
32°FSep 21Sep 24Sep 28Oct 1Oct 2Oct 4Oct 7Oct 10Oct 14
28°FSep 29Oct 2Oct 5Oct 8Oct 10Oct 13Oct 16Oct 19Oct 23
24°FOct 5Oct 9Oct 13Oct 16Oct 19Oct 23Oct 25Oct 29Nov 2
20°FOct 13Oct 18Oct 22Oct 26Oct 29Nov 1Nov 4Nov 7Nov 13
16°FOct 21Oct 29Nov 2Nov 5Nov 10Nov 13Nov 16Nov 20Nov 24

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°F1251191151111081041009589
32°F148141136131127124119114107
28°F170164158153149145140134126
24°F192185179175171166161155147
20°F220210204200195190184177170
16°F250240233227222217210204194

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
5,527
Cooling degree days, base 65°F
540
Growing degree days, base 40°F
4,898
Growing degree days, base 45°F
3,673
Growing degree days, base 50°F
2,648
Growing degree days, base 55°F
1,789
Growing degree days, base 60°F
1,087

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00300
February79900
March69607
April501051
May2648228
June4989491
July2223687
August4171632
September8448415
October3991126
November72009
December1,00700

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 4.8 km from Black Rock. 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 USW00093044 (Zuni). Public domain.