Arizona, 2021Excessive Heat in Arizona, August 3 to 4, 2021
August 3 to 4, 2021 · NWS TWC · 6 events in 6 counties and zones
Very hot temperatures were experienced in much of southeast Arizona on August 3 and 4 with high temperatures equaling or exceeding established records in a few locations, and approaching record levels in most others. The Pima County Medical Examiner confirmed that heat was the primary cause of death for two males found in the desert in Pima County.
Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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- Deaths
- 2
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 6
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
Very hot temperatures were experienced in much of southeast Arizona on August 3 and 4 with high temperatures equaling or exceeding established records in a few locations, and approaching record levels in most others. The Pima County Medical Examiner confirmed that heat was the primary cause of death for two males found in the desert in Pima County.
What forecasters said that day
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Tucson, AZ wrote its last area forecast discussion before the first event at Aug 3, 9:51 AM MST, 1 hour 9 minutes earlier.
Area forecast discussion, Aug 3, 9:51 AM MST, 1 hour 9 minutes before
Area Forecast Discussion
National Weather Service Tucson AZ
951 AM MST Tue Aug 3 2021
.SYNOPSIS...The overall trend in thunderstorm coverage will be
less for most of this week and focused south and east of Tucson.
High temperatures will trend up with excessive heat expected across
the lower deserts west of Tucson today and from Tucson west and
north on Wednesday. The coverage in daily thunderstorms may increase
this weekend. Cooler temperatures will accompany this upswing in
thunderstorm activity this weekend.
&&
.UPDATE...
Heat remains the primary concern for today and tomorrow as a strong
ridge sets up over the Desert Southwest. Excessive Heat Warning
remains in place today for areas west of Tucson which will then
expand eastward on Wednesday as Tucson temperatures reach 105+.
Storm activity remains in a lull with only a isolated showers and/or
storms south and east of Tucson towards the international border as
well as over the White Mtns this afternoon. No significant updates
to the forecast for today and tomorrow.
&&
.DISCUSSION...Main theme for the next couple of days will be less
thunderstorm activity and hotter daytime temperatures. For high
temperatures model/ensemble guidance coming in a little hotter,
especially for eastern Pima county/eastern Pinal and portions of
Graham county on Wednesday. Thus expanded the Excessive Heat
Warning, that is in effect today and Wednesday for areas W/NW of
Tucson, to the above mentioned areas on Wednesday. A few locations
will be near record highs today and Wednesday. On the T-storm
activity side for today/this evening, the best chances reside
along/near the international border and across the White
mountains.
Wednesday/Thursday: With the strong upper high in an unfavorable
position through Thursday, thunderstorm activity will be on the
very low side and confined mainly near the international border
and in the Whites. Sonora MX will be active and we may see some
shallow surges of moisture from outflows move north across the
area.
Friday: A upper level trof passing by well to our north will
suppress the upper ridge to the south, thus delaying the
advertised upswing of thunderstorm activity until the weekend. The
NBM PoPs appears on the high side versus GEFS/ENS.
Weekend: Moderate confidence on the potential for an upswing in
thunderstorm activity.
&&
.AVIATION...Valid through 05/12Z.
SKC-SCT clouds will continue this morning, then mainly SCT clouds
aft 04/18Z with isolated SHRA/TSRA psbl mainly along the NM border
and International border east of KOLS. Any SHRA/TSRA activity will
diminish aft 05/03Z. Brief MVFR conditions will be possible within
TSRA. Outside of TSRA outflows, SFC wind will generally remain less
than 12 kts through the period. Aviation discussion not updated for
TAF amendments.
&&
.FIRE WEATHER...A more quiet period for the monsoon through
Wednesday with only isolated showers and thunderstorms northeast to
southeast of Tucson. An upswing in thunderstorm activity is expected
late this week into weekend. Any thunderstorms that develop will be
capable of producing strong, gusty and erratic winds along with
locally heavy rainfall. RH values will remain well above critical
thresholds the next 7 days. 20-foot winds will generally be less
than 15 mph when not influenced by thunderstorms.
&&
.CLIMATE...Record or near record high temperatures today and Wed.
DATE Aug 03 Aug 04
FCST RCD/YR FCST RCD/YR
Ajo 111 112/1918 112 115/1969
Picacho Peak 109 112/1998 111 113/1995
Tucson Intl Airport 107 109/1994
Safford Ag Station 105 106/2009
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 11 AM to 8 PM MST Wednesday for
AZZ504-506-509.
Excessive Heat Warning from 10 AM this morning to 8 PM MST
Wednesday for AZZ501-502-505.
&&
Visit us on Facebook...Twitter...YouTube...and at weather.gov/TucsonExcessive Heat, Western Pima County
- When
- August 3, 11:00 AM MST to August 4, 8:00 PM MST
- Where
- Western Pima County forecast zone
- Reported by
- County Official
- Coordinates
- 32.097, -111.790 (the zone’s center; the record gives no point)
Very hot high temperatures of 104 to 115 degrees, or 8 to 12 degrees above normal, occurred in the lower deserts of Pima and Pinal counties August 3-4, and caused the High Heat Risk category to be reached. High temperatures on August 3 included 115 degrees at Ajo (record), 109 at Organ Pipe Cactus National Monument, 108 at Sells, and 104 at Picacho. On August 4 highs included 115 degrees at Ajo (tie), 110 at Organ Pipe Cactus National Monument, 109 at Sells (record), and 107 at Picacho. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one person found in the desert near San Miguel.
Excessive Heat, Tohono O Odham Nation
- When
- August 3, 11:00 AM MST to August 4, 8:00 PM MST
- Where
- Tohono O Odham Nation forecast zone
- Deaths
- 1 direct, 0 indirect
- Reported by
- County Official
- Coordinates
- 32.501, -111.567 (the zone’s center; the record gives no point)
Very hot high temperatures of 104 to 115 degrees, or 8 to 12 degrees above normal, occurred in the lower deserts of Pima and Pinal counties August 3-4, and caused the High Heat Risk category to be reached. High temperatures on August 3 included 115 degrees at Ajo (record), 109 at Organ Pipe Cactus National Monument, 108 at Sells, and 104 at Picacho. On August 4 highs included 115 degrees at Ajo (tie), 110 at Organ Pipe Cactus National Monument, 109 at Sells (record), and 107 at Picacho. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one person found in the desert near San Miguel.
Excessive Heat, South Central Pinal County
- When
- August 3, 11:00 AM MST to August 4, 8:00 PM MST
- Where
- South Central Pinal County forecast zone
- Reported by
- County Official
- Coordinates
- 32.904, -111.345 (the zone’s center; the record gives no point)
Very hot high temperatures of 104 to 115 degrees, or 8 to 12 degrees above normal, occurred in the lower deserts of Pima and Pinal counties August 3-4, and caused the High Heat Risk category to be reached. High temperatures on August 3 included 115 degrees at Ajo (record), 109 at Organ Pipe Cactus National Monument, 108 at Sells, and 104 at Picacho. On August 4 highs included 115 degrees at Ajo (tie), 110 at Organ Pipe Cactus National Monument, 109 at Sells (record), and 107 at Picacho. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one person found in the desert near San Miguel.
Excessive Heat, Southeast Pinal County
- When
- August 4, 11:00 AM MST to 8:00 PM MST
- Where
- Southeast Pinal County forecast zone
- Reported by
- County Official
- Coordinates
- 32.904, -111.345 (the zone’s center; the record gives no point)
Very hot high temperatures of 101 to 107 degrees, or 8 to 12 degrees above normal, occurred in the lower elevations of Graham and eastern sections of Pinal and Pima counties on August 4, and caused the High Heat Risk category to be reached. High temperatures included 107 degrees at Tucson International Airport, 102 at Safford Airport, and 101 at Green Valley, San Manuel and Duncan. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one person found in the desert near Three Points.
Excessive Heat, Tucson Metro Area
- When
- August 4, 11:00 AM MST to 8:00 PM MST
- Where
- Tucson Metro Area forecast zone
- Deaths
- 1 direct, 0 indirect
- Reported by
- County Official
- Coordinates
- 32.097, -111.790 (the zone’s center; the record gives no point)
Very hot high temperatures of 101 to 107 degrees, or 8 to 12 degrees above normal, occurred in the lower elevations of Graham and eastern sections of Pinal and Pima counties on August 4, and caused the High Heat Risk category to be reached. High temperatures included 107 degrees at Tucson International Airport, 102 at Safford Airport, and 101 at Green Valley, San Manuel and Duncan. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one person found in the desert near Three Points.
Excessive Heat, Upper Gila River and Aravaipa Valleys
- When
- August 4, 11:00 AM MST to 8:00 PM MST
- Where
- Upper Gila River and Aravaipa Valleys forecast zone
- Reported by
- County Official
- Coordinates
- 33.074, -109.563 (the zone’s center; the record gives no point)
Very hot high temperatures of 101 to 107 degrees, or 8 to 12 degrees above normal, occurred in the lower elevations of Graham and eastern sections of Pinal and Pima counties on August 4, and caused the High Heat Risk category to be reached. High temperatures included 107 degrees at Tucson International Airport, 102 at Safford Airport, and 101 at Green Valley, San Manuel and Duncan. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one person found in the desert near Three Points.
- Excessive Heat
- Heat at or above the local excessive heat warning criteria, or heat that caused deaths.
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NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 983704, 983884, 983887, 983882, 983885, 983889.