Arizona, 2023Excessive Heat in Arizona, August 1 to 6, 2023
August 1 to 6, 2023 · NWS TWC · 6 events in 6 counties and zones
High pressure aloft strengthened over Arizona and created a period of very hot temperatures August 4-6 across southeast Arizona. High temperatures were 8 to 13 degrees above normal causing the Major Heat Risk category to be reached and numerous high temperature records to be established.
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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- Floods
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- Heat and drought
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- Deaths
- 9
- 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.
High pressure aloft strengthened over Arizona and created a period of very hot temperatures August 4-6 across southeast Arizona. High temperatures were 8 to 13 degrees above normal causing the Major Heat Risk category to be reached and numerous high temperature records to be established. A total of nine heat-related fatalities were reported by the Pima County Medical Examiner.
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 1, 9:09 AM MST, 51 minutes earlier.
Area forecast discussion, Aug 1, 9:09 AM MST, 51 minutes before
Area Forecast Discussion
National Weather Service Tucson AZ
909 AM MST Tue Aug 1 2023
.SYNOPSIS...Storm chances decrease today with just a few isolated
storms this afternoon and evening. Thereafter, mostly dry conditions
from Tucson westward Wednesday and Thursday, with isolated to
scattered showers and thunderstorms for Graham, Greenlee, and
Cochise Counties. Friday through this weekend, generally dry
conditions will prevail as temperatures warm to record or near
record levels.
&&
.DISCUSSION...Latest IR/WV satellite imagery shows sunny skies this
morning across southeast Arizona. The area resides in a subsident
region on the backside of the disturbance/inverted trough that moved
through yesterday. Flow aloft is generally south to southwesterly
and the 12Z KTWC sounding came in with 1.41" of PWAT. However, the
atmosphere is continuing to dry out this morning per GOES Total PWAT
with Tucson around 1" to 1.1". Latest CAMS/HREF shows a fairly quiet
day with just isolated showers and perhaps an embedded thunderstorm
or two. With that said, coverage will be fairly limited and with the
activity that does occur, it doesn't look too impactful. This is
also supported by model soundings which show the drier and warmer
air moving in aloft throughout the day. Forecast is in good shape.
No updates this morning. See previous discussion below for
additional information.
&&
.AVIATION...valid through 02/12Z.
FEW-SCT clouds 10k-14k AGL this afternoon and evening. Subsidence
behind yesterday's inverted trough as well as slightly drier air
will inhibit convection today. CAMs not showing many storms today
with just a few isolated -TSRA possible in the afternoon and
likely not impacting any terminals. Sfc winds variable less than 6
kts this morning becoming southwesterly to northwesterly 8-10 kts
with gusts 15-20 kts this afternoon and early evening. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Storms will likely struggle today with limited
strength and coverage. Wednesday and Thursday expect isolated storms
mainly south and east of Tucson then mostly dry Friday into the
weekend. Although sustained 20-foot winds will generally remain
under 15 mph, gusts to around 25 mph may occur each afternoon.
Temperatures closer to normals today but will quickly heat back up
Wednesday and beyond, with near record highs returning Friday into
the weekend. Valley min RH readings will generally range between 20-
30% today with conditions drying out to 10-20% for Wednesday and
beyond.
&&
.PREV DISCUSSION...Skies are beginning to clear across southeast
Arizona with PWAT values ranging from 1.0"-1.4". The inverted trough
that helped storms out today is now to the north with high pressure
centered over Texas. Storms will likely struggle today thanks to
subsidence in the wake of the trough and slightly drier air moving
in. The HREF and other CAMs show minimal convection today with maybe
just a few weak short-lived isolated cells. Nothing like has
happened the past few days. High temperatures will top out a couple
degrees above normal.
Wednesday and Thursday look to be a bit more active than today with
just enough moisture for isolated storms mainly south and east of
Tucson. Main threats with any of these storm will be strong outflow
winds. After Thursday southeast Arizona really begins to dry out
with PWAT values dropping down to 1.1" or less through the weekend.
This is a result of high pressure moving back west over Arizona and
northern Mexico cutting moisture transport and warming the mid-
levels. Moisture values will be much below normal for this time of
year which could lead to a complete lack of thunderstorms Friday
through the weekend. Or if any form they would be short-lived and
mainly confined to the international border or higher terrain.
The main story will be the return of excessive heat Friday into the
weekend. During this time temperatures will likely be at or near
record levels. Friday into Sunday Tucson International Airport will
have a 44%-54% chance to hit 110 degrees or higher with the best
chance Saturday. Because of this and in coordination with PSR an
Excessive Heat Watch is in effect Friday through Sunday for portions
of Pima, Pinal, Santa Cruz, Graham, and Greenlee Counties.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Friday morning through Sunday evening
for AZZ502>506-509.
&&
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In the hours before
Local storm report, Aug 1, 7:24 AM MST, 2 hours 36 minutes before
Preliminary Local Storm Report...Corrected
National Weather Service Tucson AZ
724 AM MST Tue Aug 1 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0552 PM Tstm Wnd Gst 6 SW Tucson 32.13N 110.95W
07/31/2023 M58 MPH Pima AZ ASOS
Corrects previous tstm wnd gst report from 6
SW Tucson. ASOS station KTUS Tucson
International Airport.
&&
KDLocal storm report, Aug 1, 8:15 AM MST, 1 hour 45 minutes before
Preliminary Local Storm Report
National Weather Service Tucson AZ
815 AM MST Tue Aug 1 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0815 PM Flash Flood 10 SSW Oro Valley 32.29N 111.04W
07/31/2023 Pima AZ Broadcast Media
Silverbell Rd south of Camino Del Cerro.
&&
KDLocal storm report, Aug 1, 8:37 AM MST, 1 hour 23 minutes before
Preliminary Local Storm Report
National Weather Service Tucson AZ
837 AM MST Tue Aug 1 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0715 PM Tstm Wnd Dmg 6 SE Marana 32.35N 111.11W
07/31/2023 Pima AZ Public
Trees down blocking Silverbell Rd. north of
Cortaro Farms Rd. reported on social media.
Time estimated from radar.
&&
KDLocal storm report, Aug 1, 9:56 AM MST, 4 minutes before
Preliminary Local Storm Report
National Weather Service Tucson AZ
956 AM MST Tue Aug 1 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0640 PM Tstm Wnd Dmg 11 SW Tucson 32.09N 111.02W
07/31/2023 Pima AZ County Official
Power poles down causing closure of Mission
Rd. south of Campus Dr. Time estimated from
radar.
0800 PM Flash Flood 8 WSW Tucson 32.14N 111.02W
07/31/2023 Pima AZ County Official
Mission Rd. between Valencia and Drexel
closed due to flooding.
&&Excessive Heat, Western Pima County
- When
- August 1, 10:00 AM MST to August 3, 8:00 PM MST
- Where
- Western Pima County forecast zone
- Reported by
- Mesonet
- Coordinates
- 32.097, -111.790 (the zone’s center; the record gives no point)
Very hot temperatures up to 10 degrees above normal caused the Major Heat Risk category to be reached across western Pima County and southern Pinal County August 4-6. A record high of 107 degrees occurred at San Manuel on August 5. Other high temperatures included 112 at Ajo on August 4 and 5; 110 at Picacho Peak on all three days; and 109 at Ajo on August 4.
Excessive Heat, South Central Pinal County
- When
- August 1, 10:00 AM MST to August 3, 8:00 PM MST
- Where
- South Central Pinal County forecast zone
- Reported by
- Mesonet
- Coordinates
- 32.904, -111.345 (the zone’s center; the record gives no point)
Very hot temperatures up to 10 degrees above normal caused the Major Heat Risk category to be reached across western Pima County and southern Pinal County August 4-6. A record high of 107 degrees occurred at San Manuel on August 5. Other high temperatures included 112 at Ajo on August 4 and 5; 110 at Picacho Peak on all three days; and 109 at Ajo on August 4.
Excessive Heat, Southeast Pinal County
- When
- August 1, 10:00 AM MST to August 3, 8:00 PM MST
- Where
- Southeast Pinal County forecast zone
- Reported by
- Mesonet
- Coordinates
- 32.904, -111.345 (the zone’s center; the record gives no point)
Very hot temperatures up to 10 degrees above normal caused the Major Heat Risk category to be reached across western Pima County and southern Pinal County August 4-6. A record high of 107 degrees occurred at San Manuel on August 5. Other high temperatures included 112 at Ajo on August 4 and 5; 110 at Picacho Peak on all three days; and 109 at Ajo on August 4.
Excessive Heat, Tohono O Odham Nation
- When
- August 4, 10:00 AM MST to August 6, 8:00 PM MST
- Where
- Tohono O Odham Nation forecast zone
- Deaths
- 3 direct, 0 indirect
- Reported by
- County Official
- Coordinates
- 32.501, -111.567 (the zone’s center; the record gives no point)
Very hot temperatures of 8 to 13 degrees above normal caused the Major Heat Risk category to be reached across the Tohono O'odham Nation, southeast Pima County, and the lower elevations of Santa Cruz County August 4-6. Record highs at Sells included 109 degrees on August 4 and 5; and 107 at Nogales on August 5. The Pima County Medical Examiner determined that heat was the primary cause of death for four individuals found in the desert during the period; one northwest of Tubac on the 4th and three others on the Tohono O'odham Nation on the 5th in the Sells and Topawa areas.
Excessive Heat, Upper Santa Cruz River and Altar Valleys
- When
- August 4, 10:00 AM MST to August 6, 8:00 PM MST
- Where
- Upper Santa Cruz River and Altar Valleys forecast zone
- Deaths
- 1 direct, 0 indirect
- Reported by
- County Official
- Coordinates
- 31.812, -111.318 (the zone’s center; the record gives no point)
Very hot temperatures of 8 to 13 degrees above normal caused the Major Heat Risk category to be reached across the Tohono O'odham Nation, southeast Pima County, and the lower elevations of Santa Cruz County August 4-6. Record highs at Sells included 109 degrees on August 4 and 5; and 107 at Nogales on August 5. The Pima County Medical Examiner determined that heat was the primary cause of death for four individuals found in the desert during the period; one northwest of Tubac on the 4th and three others on the Tohono O'odham Nation on the 5th in the Sells and Topawa areas.
Excessive Heat, Tucson Metro Area
- When
- August 4, 10:00 AM MST to August 6, 8:00 PM MST
- Where
- Tucson Metro Area forecast zone
- Deaths
- 1 direct, 4 indirect
- Reported by
- County Official
- Coordinates
- 32.097, -111.790 (the zone’s center; the record gives no point)
Very hot temperatures of 8 to 11 degrees above normal caused the Major Heat Risk category to be reached across the Tucson Metro area August 4-6. Record highs at Tucson International Airport included 109 degrees on August 4 and 110 on August 5. The Pima County Medical Examiner determined that heat was the primary cause of death for one individual who was walking outdoors on the 5th. Heat was found to be a contributing factor in the death of four individuals. Two were found outdoors and also experienced a complicating factor of drug toxicity. Two were found indoors with a nonfunctioning or nonexistent AC unit and had complicating factors of drug toxicity or another health condition.
- Excessive Heat
- Heat at or above the local excessive heat warning criteria, or heat that caused deaths.
After NWS Directive 10-1605, the rules offices file Storm Data by.
- Excessive Heat and Heat in Arizona, August 1 to 7, 202358 deaths · 38 events
- Excessive Heat and Heat in Texas, August 1 to 14, 202315 deaths · 501 injured · 92 events
- Heat in Arizona, August 1 to 3, 202311 deaths · 3 events
- Excessive Heat in Oklahoma, August 1 to 4, 202332 injured · 25 events
- Flash Flooding and Flooding in Utah, August 1 to 4, 2023$21 million · 1 in hail · 43 events
- Excessive Heat and Heat in Texas, August 1 to 5, 20231 death · 25 events
- Tornado and Hail in North Dakota, August 1, 2023$5.3 million · 1.75 in hail · 51 events
- Wildfire in Washington, August 1 to 31, 2023$9.9 million · 1 event
- Wildfire in Idaho, August 1 to 30, 2023$9.2 million · 1 event
- Drought in Louisiana, August 1 to 31, 2023$4.0 million · 4 events
- Drought in Missouri, August 1 to 31, 2023$1.9 million · 17 events
- Wildfire in Colorado, August 1 to 31, 2023$4.0 million · 1 event
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 2026-09-30. Each event’s entry at NCEI: 1134751, 1134752, 1134753, 1134754, 1134755, 1134756.