805
FXUS64 KBRO 200527 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1227 AM CDT Sun Sep 20 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1224 AM CDT Sun Sep 20 2026

 - Major to Extreme Heat Risk continues across the populated RGV
   through at least Tuesday, with Moderate to Major across the
   rural areas where overnight temperatures will be a little lower
   each day.

 - Record heat for the month-to-date will remain the story through
   the seven day period and beyond.

 - Generally dry weather will prevail through Tuesday or
   Wednesday, with some potential for increased rain chances and
   coverage by Wednesday or Thursday. That said...overall area-
   wide rainfall for the week will remain below seasonal averages,
   which is a little over 1".

&&

.DISCUSSION...
Issued at 1106 PM CDT Sat Sep 19 2026

The big picture for the next seven days, through the last full week
of September 2026?  The heat dome refuses to loosen its grip on the
southern tip of Texas. After a single-day window of "typical"
rainfall (mainly for the upper Valley and Brush Country) on Friday,
another slug of dry air followed today, with zero rainfall on
a(nother) day when area-wide average rainfall is around 0.20".  The
dry air remains entrenched Sunday and likely for most on Monday,
which means status quo for daytime and overnight temperatures.
Perhaps the only good news is that longer nights and calm late
night/early morning winds are nudging morning temperatures into the
70s, including the urban areas. Afternoon highs are a smidge lower
than a week ago...but still running 6 to 9 degrees above late
September averages and will continue to do so through at least
Tuesday.

As for Tuesday...NBM is returning better rain chances to the region,
but model trends are drying a bit so with the 500 mb ridge still
parked over all of Texas, any deeper moisture is likely to remain in
Mexico for one more day. On Wednesday, there is a hint that the
ridge axis will shift eastward into the western Gulf, which could
open the door to a touch more deep-layer moisture and hence a bit
more coverage of rain, likely following the mid-late morning start
near the coast and reaching farther inland by early to mid
afternoon. Thursday may offer the best opportunity for at least
"average" coverage for late September, before the ridge slides
westward once again Friday into next weekend, with plenty of heat
underneath it despite broad low-level east-northeast flow similar to
what we`re seeing today.

Bottom line?  September is locking in on a record-shattering
temperature month, along with drier-to-much drier than average
(average is 4.5" west to 6" east, and we`re sitting at 5-25% of the
month-to-date values (about 3.5 to 5")for all but a few pockets.

Finally...that generally persistent broad but not too strong east-
northeast flow will maintain a moderate rip current intensity on
most days.  Such days when the waves are enticing and the surf is
warm (mid 80s) can be deceptive to poor swimmers who can get trapped
in a rip...so folks venturing to the beach need to be extra
vigilant, as we`ve had more drownings on moderate days than any
other type since 2008.

&&

.AVIATION...
(06Z TAFS)
Issued at 1224 AM CDT Sun Sep 20 2026

Mostly clear skies with light and variable winds prevail across
Deep South Texas early this morning. Light winds overnight are
forecast to increase and become easterly later this morning into
the afternoon. VFR conditons are expected for the next 24 hours.

&&

.MARINE...
Issued at 1106 PM CDT Sat Sep 19 2026

Through at least Tuesday, fair conditions with isolated to
perhaps scattered mainly overnight-late morning showers is expected.
Broad but light to occasionally moderate easterly flow will prevail
with the daily sea breeze nudging Laguna Madre winds up to 10-15
knots for a spell between 2 PM and 8 PM most days. Could see a bit
more coverage of showers and a few storms Wednesday and
Thursday...but nothing more than average for this time of year and
confidence is low at this point given no significant forcing
mechanism as the persistent upper level ridge dominates. Overall,
favorable boating conditions especially given that its September.

&&

.CLIMATE...
Issued at 1106 PM CDT Sat Sep 19 2026

Here are some staggering temperature numbers for September
and Astronomical Summer (June 21 to September 18), which is nearing
its end, so far:

Brownsville (since 1878)
September 1-18                        June 21 - September 18
90.3 (#1, prior: 89.1, 2023)         89.1 (#2, prior: 89.3, 2023)

Harlingen (since 1912)
September 1-18                       June 21 - September 18
88.4 (#1, prior: 88, 2023)           87.8 (#2, prior: 88.9, 2023)

McAllen (since 1941)
September 1-18        June 21 - September 18
92.6 (#1, prior: 89.9, 2023)         91.3 (#1, prior: 90.7, 2009)

Raymondville (since 1913)
September 1-18        June 21 - September 18
90.2 (#1, prior: 88.3, 2023)         88.9 (#2, prior: 89.2, 2023)

Weslaco (since 1914)
September 1-18        June 21 - September 18
90.3 (#1, prior: 88.8, 2023)         89.1 (#2, prior: 89.3, 2023)

Other interesting statistics:
*Brownsville set another maximum temperature record (99) on the
19th. That makes 13 new records in September alone, and 33 for the
calendar year so far.
*McAllen reached 59 straight 100 degree days, putting more distance
between 2026 and the prior record (49) in 2009.
*McAllen also reached 89 days with 100 degrees or higher, with the
record of 97 (set in 2023) in clear range.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             97  80  96  80 /  10   0  30   0
HARLINGEN              100  76  99  76 /  10   0  20   0
MCALLEN                103  79 102  79 /   0   0  30   0
RIO GRANDE CITY        102  78 102  77 /   0   0  10   0
SOUTH PADRE ISLAND      89  82  89  82 /  10  10  10   0
BAYVIEW/PORT ISABEL     95  79  95  79 /  10   0  10   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

SHORT TERM...52-Goldsmith
LONG TERM....52-Goldsmith
AVIATION...63-KC