Arizona, 2021Excessive Heat and Heat in Arizona, September 11 to 14, 2021
September 11 to 14, 2021 · NWS TWC · 6 events in 3 counties and zones
Very hot temperatures were experienced west and south of Tucson September 11 through 14. The hottest two days were the 12th and 13th when high temperatures fell just shy of records across much of Pima County and topped out between 104 and 109 degrees.
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
- 7
- 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 west and south of Tucson September 11 through 14. The hottest two days were the 12th and 13th when high temperatures fell just shy of records across much of Pima County and topped out between 104 and 109 degrees. During the four day period, the Pima County Medical Examiner confirmed that heat was the primary cause of death for seven individuals found in the desert, one at Organ Pipe Cactus National Monument, five on the Tohono O'odham Nation, and one in Santa Cruz 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 Sep 11, 8:32 AM MST, 1 hour 28 minutes earlier.
Area forecast discussion, Sep 11, 8:32 AM MST, 1 hour 28 minutes before
Area Forecast Discussion
National Weather Service Tucson AZ
832 AM MST Sat Sep 11 2021
.SYNOPSIS...Hot and dry conditions are expected across most of
southeast Arizona into early next week. Near record highs are
possible Sunday and Monday.
&&
.DISCUSSION...The weather across the desert southwest will be
dominated by strong high pressure aloft currently centered over New
Mexico. Flow around the high will continue to import drier air
centered over New Mexico, west Texas and Chihuahua, Mexico as noted
on Water Vapor satellite imagery and Satellite Layer Blended Total
Precipitable Water Imagery (Blended TPW). While the KTWC 210911/12
sounding shows PWAT at 1.09 inches, the aforementioned satellite
imagery indicates values of less than .50 inches over far eastern
portions of the forecast area along the New Mexico state line and
directly to our east/southeast. Starting on Sunday the upper ridge
becomes elongated and stretches across much of the southern tier of
states. This will help to increase temperatures across southeast
Arizona and an Excessive Heat Warning remains in effect for areas
west of Tucson (central/western Pima county) from 10 am Sunday
through 8 pm Monday.
The current position of the upper high has allowed some moisture
from the remnants of Olaf (south of the Baja Spur) to be pulled
northward on the western flak of the high circulation across far
western portions of Pima county. Blended TPW indicates around 1.30
inches over far western Pima County in the vicinity of Ajo and Organ
Pipe. Given a few showers/storms fired across this area late
yesterday afternoon/early evening with even less moisture, will
update the grids/text products for slight chance pops across the
western half of Pima County (roughly west of Sells) this afternoon
and evening. Otherwise, forecast looks good and on track.
&&
.AVIATION...Valid through 12/12Z.
SCT to lcly BKN clouds 10k-15k ft MSL mnly west of KSAD-KFHU line,
otrw CLR. SFC winds less than 12 kts through the period. Aviation
not updated for TAF amendments.
&&
.FIRE WEATHER...Mostly dry conditions and above average temperatures
are expected through early next week. Surface winds will follow
normal wind trends less than 15 mph. Minimum RH values will be
between 15-25 percent each afternoon through early next week.
&&
.CLIMATE...Near record high temperatures are in the forecast for
southeast Arizona Sunday and Monday.
DATE Sep 12 Sep 13
FCST RCD/YR FCST RCD/YR
Tucson Intl airport 104 106/2017 103 107/1895
Ajo 109 111/2007 108 111/1971
Organ Pipe Cactus 108 110/1971 107 109/2019
Picacho Peak 105 108/1990 105 109/2000
Safford Ag Station 101 101/1971 100 100/2004
Sierra Vista 94 98/1983 94 97/2017
Tombstone 95 99/2016 95 99/2016
Willcox 96 99/2017 96 101/2017
&&
.PREV DISCUSSION...Strong high pressure over the desert southwest
will dominate our weather into early next week. The high center is
in a traditionally good spot to bring in moisture from the south and
southeast, however New Mexico, Chihuahua and even Durango are
currently rather dry as we approach the end of the Monsoon. The flow
is actually shunting any the relatively deeper moisture pushed up
from Olaf (now a remnant near southern Baja) westward and keeping it
out of most of our area. Excessive heat levels a concern, especially
across the lower deserts west of Tucson.
The ridge will break down early next week as the synoptic pattern
sags broad troughiness across northern tier states and we gain a
zonal flow. This will also probably keep any inverted trough
developing through southern Texas from making much progress toward
our area.
A weak moisture push from the south is possible the second half of
next week as the flow weakens and a high center tries to
reconsolidate near southern New Mexico. We will likely be on the dry
side until then with limited to no thunderstorm chances.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 10 AM Sunday to 8 PM MST Monday for
AZZ501-502.
&&
Discussion...Zell
Prev Discussion/Aviation/Fire Weather...Meyer/Glueck
Visit us on Facebook...Twitter...YouTube...and at weather.gov/TucsonHeat, Tohono O Odham Nation
- When
- September 11, 10:00 AM MST to 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)
Hot temperatures 3 to 5 degrees above normal, around 105 degrees, were experienced across the Tohono O'odham Nation causing the Moderate Heat Risk category to be reached on September 11. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one female found in the desert west of Vamori.
Heat, Upper Santa Cruz River and Altar Valleys
- When
- September 12, 10:00 AM MST to 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)
Hot temperatures 4 to 6 degrees above normal, in the upper 90s, were experienced in the lower elevations of Santa Cruz County causing the Moderate Heat Risk category to be reached on September 12. The Pima County Medical Examiner confirmed that heat was the primary cause of death for one male found in the desert near Amado.
Excessive Heat, Western Pima County
- When
- September 12, 10:00 AM MST to September 13, 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 high temperatures of 105 to 109 degrees, or 5 to 10 degrees above normal, occurred in the lower deserts of western Pima County and the Tohono O'odham Nation September 12-13, and caused the High Heat Risk category to be reached. While temperatures fell just shy of records, the Pima County Medical Examiner confirmed that heat was the primary cause of death for three persons found in the desert on the Tohono O'odham Nation.
Excessive Heat, Tohono O Odham Nation
- When
- September 12, 10:00 AM MST to September 13, 8:00 PM MST
- Where
- Tohono O Odham Nation forecast zone
- Deaths
- 3 direct, 0 indirect
- Reported by
- Mesonet
- Coordinates
- 32.501, -111.567 (the zone’s center; the record gives no point)
Very hot high temperatures of 105 to 109 degrees, or 5 to 10 degrees above normal, occurred in the lower deserts of western Pima County and the Tohono O'odham Nation September 12-13, and caused the High Heat Risk category to be reached. While temperatures fell just shy of records, the Pima County Medical Examiner confirmed that heat was the primary cause of death for three persons found in the desert on the Tohono O'odham Nation, one female north of San Simon on the 12th, another female southwest of Vamori and one male west of Cowlic on the 13th.
Heat, Tohono O Odham Nation
- When
- September 14, 10:00 AM MST to 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)
Hot temperatures 3 to 5 degrees above normal, around 105 degrees, were experienced across the western and central Pima County causing the Moderate Heat Risk category to be reached on September 14. The Pima County Medical Examiner confirmed that heat was the primary cause of death for two males found in the desert, one on the eastern edge of the Organ Pipe Cactus National Monument and another on the Tohono O'odham Nation northwest of Kohatk.
Heat, Western Pima County
- When
- September 14, 10:00 AM MST to 8:00 PM MST
- Where
- Western Pima County 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)
Hot temperatures 3 to 5 degrees above normal, around 105 degrees, were experienced across the western and central Pima County causing the Moderate Heat Risk category to be reached on September 14. The Pima County Medical Examiner confirmed that heat was the primary cause of death for two males found in the desert, one on the eastern edge of the Organ Pipe Cactus National Monument and another on the Tohono O'odham Nation northwest of Kohatk.
- Heat
- Heat below excessive heat criteria that still caused deaths, injuries or significant impacts.
- 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.
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- Rip Current in South Carolina, September 11, 20211 event
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- Lightning Strike in Florida, September 11, 2021$2,000 · 1 event
- Damaging Wind in Utah, September 11, 202152 kt wind · 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 2026-09-24. Each event’s entry at NCEI: 986808, 986811, 986812, 986813, 986809, 986810.