A mid level ridge of high pressure allowed for effective heating across the Rio Grande Valley and Deep South Texas on June 21st. These hot temperatures combined with elevated dew points and relative humidity values lead to heat indices exceeding 115 degrees for just over 2 hours across portions of the western counties of the Lower Valley.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS BRO wrote it up.
A mid level ridge of high pressure allowed for effective heating across the Rio Grande Valley and Deep South Texas on June 21st. These hot temperatures combined with elevated dew points and relative humidity values lead to heat indices exceeding 115 degrees for just over 2 hours across portions of the western counties of the Lower Valley. Other areas reported heat indices of 111 degrees or greater for a couple of hours in the afternoon as well. An Excessive Heat Warning was in effect for Zapata, Starr, and Southern Hidalgo County and a Heat Advisory was in effect for Northern Hidalgo and Jim Hogg County.
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 Jun 21, 1:23 PM CST, 37 minutes earlier.
Area Forecast Discussion
National Weather Service Brownsville TX
223 PM CDT Mon Jun 21 2021
.SHORT TERM (Now through Tuesday Night): Temperatures late this
afternoon will continue to be warm with Excessive Heat Warnings
for Zapata, Starr and southern Hidalgo Counties into early
evening, and Heat Advisories for northern Hidalgo and Jim Hogg
Counties also into early evening. Overnight, conditions will
remain sultry with lows in the upper 70s and low 80s with
temperatures feeling like the upper 80s to low 90s. Later tonight,
a cold front will move southward into central Texas but should
remain well north of the CWA. Ahead of this frontal boundary,
abundant moisture, mid level energy and southeasterly winds will
allow for an increasing chance of shower and thunderstorm
development. Chances of convection will continue increase through
the day Tuesday and PWATS will remain well over 2 inches allowing
for the this activity to produce a pretty decent amount of rain.
Models are suggesting a half to one inch of rainfall possible in
many locations and areas that see multiple rounds or slow moving
storms could see upwards of 2 inches. Thanks to the increased
cloud cover and potential rainfall, temperatures will be a bit
lower tomorrow with highs in the low to mid 90s. Tuesday night,
rain chances begin to decrease with overnight lows in the mid to
upper 70s.
&&
.LONG TERM (Wednesday through Monday): Unsettled weather on Tuesday
will bleed over into Wednesday, with isolated, mainly coastal
based showers during the day. Mid level ridging centered over West
Texas and New Mexico will build more confidently over Texas the
latter half of the week. A mid level trough will dig south over
the Plains late in the week and into the weekend, breaking down
the ridge and supporting and underlying front that will move into
Texas Saturday and Sunday. It doesn't look like the front will
push into the CWA, but weak surface troughing will set up over the
area, giving rise to slightly enhanced rain chances Sunday
through Tuesday. Felt that the National Blend was overachieving on
dew points so trimmed those back a skosh. The result is less
confidence than before with heat advisory conditions over and
around Starr County Wednesday through Saturday. The rest of the
long term looks rather routine. Slightly above average high
temperatures in the 90s to the century mark and above out west.
Overnight lows from the mid 70s to near 80. A mix of clouds and
sun each day with persistent southeast winds.
&&
.MARINE:
Now through Tuesday Night...The pressure gradient along the lower
Texas coast will continue to weaken allowing for more favorable
marine conditions to slowly return. Small craft should continue to
exercise caution on the Laguna Madre and Gulf waters through this
evening. Tuesday, favorable seas return outside any shower or
thunderstorm activity.
Wednesday through Saturday Night...Light to moderate southeast
winds and moderate seas will prevail through the long term. Winds
may briefly strengthen to small craft should exercise caution
strength (15 to 20 kts) at times. Isolated to scattered showers
and thunderstorms will be possible from time to time. As the week
evolves, ridging will build over the area, and high pressure will
remain dominant across the North gulf, locking in southeast flow
through the end of the long term.
&&
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL 82 88 79 92 / 20 60 40 20
BROWNSVILLE 82 91 79 94 / 20 60 40 20
HARLINGEN 81 90 77 94 / 20 60 30 20
MCALLEN 81 91 78 96 / 20 60 30 20
RIO GRANDE CITY 80 93 77 100 / 20 50 40 20
SOUTH PADRE ISLAND 83 86 81 87 / 20 60 40 20
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening for TXZ249-353.
Excessive Heat Warning until 7 PM CDT this evening for TXZ248-
252-253.
GM...None.
&&
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
68-McGinnis/54-BHM/67-MejiaHazardous Weather Outlook...UPDATED National Weather Service Brownsville TX 1005 AM CDT Mon Jun 21 2021 TXZ248>257-351-353-221515- Zapata-Jim Hogg-Brooks-Inland Kenedy-Starr-Southern Hidalgo- Inland Willacy-Inland Cameron-Coastal Willacy-Coastal Cameron- Coastal Kenedy-Northern Hidalgo- 1005 AM CDT Mon Jun 21 2021 This Hazardous Weather Outlook is for portions of Deep South Texas. .DAY ONE...Today and Tonight There is a Moderate Risk of rip currents at the beaches of South Padre Island and at Boca Chica Beach. An excessive heat warning is in effect for Zapata, Starr and Southern Hidalgo from 1 to 7 PM. A Heat advisory is in effect for Jim Hogg and Northern Hidalgo from 1 to 7 PM. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms on Tuesday may produce gusty winds, and some locally heavy rainfall. Heat advisories may be needed for a few hours each afternoon for Starr county Wednesday and Thursday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. GMZ130-132-135-150-155-170-175-221515- Laguna Madre from the Port of Brownsville to the Arroyo Colorado- Laguna Madre from the Arroyo Colorado To 5 NM north of Port Mansfield TX- Laguna Madre from 5 nm north of Port Mansfield to Baffin Bay TX- Coastal waters from Port Mansfield to the Rio Grande out 20 nm- Coastal waters from Baffin Bay to Port Mansfield out 20 nm- Waters from Port Mansfield to the Rio Grande extending from 20 to 60 nm- Waters from Baffin Bay to Port Mansfield extending from 20 to 60 nm- 1005 AM CDT Mon Jun 21 2021 This Hazardous Weather Outlook is for portions of The Gulf of Mexico and The Laguna Madre. .DAY ONE...Today and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday A few strong thunderstorms Tuesday may produce brief gusty winds, some ground to water lightning strikes and locally higher seas. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
2 excessive heat, 2 heat. Local standard time, as filed.
The Automated Weather Observing System at Zapata County Airport, 4 miles northeast of the city, reported 3 hours of heat indices exceeding 115 degrees starting at 3 PM CDT. There were no known heat related illnesses or casualties as of this writing.
The Automated Weather Observing System at the Zapata County Airport reported 3 hours of heat indices exceeding 115 degrees starting at 3 PM CDT, and by proxy, it's safe to assume that Starr County received similar conditions for this time period. The Mesowest location at Falcon Lake reported excessive heat values of 119 to 123, but these are considered several degrees too high based on comparative observations in past events.
There were no known heat related casualties in these areas as of this writing.
The Automated Weather Observing System at the South Texas International Airport 11 miles north of Edinburg, along FM 490, reported 3 hours of heat indices reaching or exceeding 111 degrees beginning at 3 PM CDT. There was about a 30 minute period of heat indices exceeding 115 degrees beginning around 3:30 PM, but it was not long enough to meet Excessive Heat Criteria.
The Automated Weather Observing System at the South Texas International Airport 11 miles north of Edinburg, along FM 490, reported 3 hours of heat indices reaching or exceeding 111 degrees beginning at 3 PM CDT. There was about a 30 minute period of heat indices exceeding 115 degrees beginning around 3:30 PM, but it was not long enough to meet Excessive Heat Criteria. The sensor location straddles the NWS forecast zones of northern and southern Hidalgo County.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Texas in 2021Every state in 2021This day in weather historyWarnings in Texas, June 2021
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: 970217, 970219, 970228, 970230.