Name: Heat in Texas, August 21, 2024
Start: 2024-08-21T11:52
End: 2024-08-21T17:30
Location: Texas

Where it happened

Every event with a place to put it; 3 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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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 3

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.

What happened

The episode as NWS BRO wrote it up.

The strong atmospheric pattern known as La Canicula, which features a high pressure ridge or heat dome, combined with sufficient surface moisture from light southeast winds to provide several hours of heat index (apparent temperature) at or above 111F each afternoon for several hours in portions of Cameron and southern Hidalgo County. Other locations, including Willacy, Brooks, and Kenedy County, touched 111 for an hour or less, which is shy of local criteria for a heat event (111 or higher for at least 2 hours).

There were no known direct injuries or fatalities from the heat, though local hospitalization records for the May through August period showed another year of high admittance rates due to heat-related stress.

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 Brownsville, TX wrote its last area forecast discussion before the first event at Aug 21, 11:25 AM CST, 27 minutes earlier.

Area forecast discussion, Aug 21, 11:25 AM CST, 27 minutes before

Area Forecast Discussion
National Weather Service Brownsville TX
1225 PM CDT Wed Aug 21 2024

...New AVIATION...

.SHORT TERM...
(Today through Thursday)
Issued at 230 AM CDT Wed Aug 21 2024

Dangerous heat will be the main concern during this portion of
the total forecast. Broad 500 mb high pressure centered over New
Mexico and the Texas Panhandle will be the dominant weather
feature over the BRO CWFA. Combined with relative humidity
percentages, the result will be greatly elevated heat indices for
the afternoon and early evening hours. As a result, a HEAT
ADVISORY is in effect for Brooks, Kenedy, Willacy, Cameron, and
Hidalgo counties today, with another HEAT ADVISORY likely for
Thursday for the same, if not slightly larger, area. The mid-level
ridge will also produce dry weather, although some very isolated
showers cannot be ruled out for the far offshore Gulf of Mexico
waters, especially today.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 230 AM CDT Wed Aug 21 2024

The long term forecast period will be largely dominated by the
mid/upper level ridge. This will cause hot and mostly rain-free
conditions to persist through the rest of the work week and into the
first half of the weekend. Meanwhile on the surface, southeasterly
winds are expected to persist that will bring in plenty of low-level
moisture to the region, which will bring in plenty of humidity to
the area. This combined with the temperatures, will likely result in
Heat Advisories being needed for parts of Deep South Texas and the
Rio Grande Valley. Heat indices are expected to be in the range of
109 to 111 for most of the long term forecast period.

As for the temperatures, the high temperatures start out in the
triple digits for most of the the region, but by the end of the long
term forecast period the highs are mostly in the mid 90s. As for the
low temperatures, they are expected to remain in the 70s with a few
places getting into the low 80s.

During the second half of the weekend, an inverted trough will
approach the Lower Texas Coast and could produce some unsettled
weather during the early parts of next work week. With PWATS
approaching 2 inches, the additional moisture should help increase
rain chances for next week. However, not all of the models agree
with this solution, thus confidence is not high at this point.
Should clearer skies prevail, then high temperatures should be in
the mid 90s and heat indices be around 110.

&&

.AVIATION...
(18Z TAFS)
Issued at 1225 PM CDT Wed Aug 21 2024

VFR will prevail through the forecast period at all TAF sites.
Expect southerly to southeasterly winds generally around or below
10 knots through late this evening, with light and variable winds
tonight. Southeast winds should increase in speed by mid to late
morning tomorrow. Otherwise, FEW to SCT cumulus clouds will
persist through the period.

&&

.MARINE...
Issued at 230 AM CDT Wed Aug 21 2024

Today through Thursday...Buoy 42020 reported south winds around
10 knots gusting to around 14 knots with seas slightly under 1.5
feet with a period of 5 seconds at 1:20 CDT/6:20 UTC. Light to
moderate winds and low to moderate seas will prevail along the
Lower Texas Coast courtesy of high pressure over the western Gulf
of Mexico. Neither Small Craft Should Exercise Caution nor Small
Craft Advisory are likely to be needed.

Thursday night through Tuesday...Favorable conditions are expected
to persist with light to moderate southeasterly winds and low to
moderate seas. Slight chance of rain returns towards the end of the
weekend and early part of the work week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             99  80  97  79 /  10   0   0   0
HARLINGEN              101  77  98  75 /   0   0   0   0
MCALLEN                106  80 103  78 /   0   0   0   0
RIO GRANDE CITY        104  79 102  77 /   0   0   0   0
SOUTH PADRE ISLAND      91  83  90  83 /   0   0   0   0
BAYVIEW/PORT ISABEL     96  78  94  78 /   0   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening for TXZ250-251-253>255-
     351-353>355.

GM...None.
&&

SHORT TERM...99
LONG TERM....99
AVIATION...22-Garcia

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 heat. Local standard time, as filed.

Heat, Cameron

When: August 21, 11:52 AM CST to 4:52 PM CST
Where: Cameron forecast zone
Reported by: ASOS
Coordinates: 26.152, -97.453 (the zone’s center; the record gives no point)

The Automated Surface Observing System (ASOS) sensor at Valley International Airport in Harlingen (KHRL) reported 5 hours of heat index of 111F or higher, peaking at 114 at 1 to 2 PM CST. The ASOS sensor at Brownsville/South Padre International Airport (KBRO) had an estimated 1.75 hours of similar conditions, peaking at 115F at around the same time.

Heat, Coastal Cameron

When: August 21, 12:30 PM CST to 2:30 PM CST
Where: Coastal Cameron forecast zone
Reported by: ASOS
Coordinates: 26.152, -97.453 (the zone’s center; the record gives no point)

The Automated Surface Observing System (ASOS) sensor near Bayview (KPIL) recorded a peak heat index of 115F at around 1 PM CST, with around 2 hours at or above 111F between roughly 1230 and 230 PM CST.

Heat, Southern Hidalgo County

When: August 21, 1:53 PM CST to 5:30 PM CST
Where: Southern Hidalgo County forecast zone
Reported by: ASOS
Coordinates: 26.397, -98.181 (the zone’s center; the record gives no point)

The Automated Surface Observing System (ASOS) sensor at McAllen (KMFE) recorded a little more than 2 hours total of heat index values of 111F or higher between 2 PM and 530 PM CST, though the period was broken by a short break right around 4 PM (values just below 111F). Peak heat index reached just below 112F during this window.

What these are

Heat: Heat below excessive heat criteria that still caused deaths, injuries or significant impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Texas in 2024 Every state in 2024 This day in weather history Warnings in Texas, August 2024

Sources

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: 1214256, 1214258, 1214260.