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National Weather Service Forecast Discussion

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327
FXUS64 KHGX 181700
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1200 PM CDT Fri Sep 18 2026

...New DISCUSSION, AVIATION, MARINE...

.KEY MESSAGES...

 - Hot and dry, with lower humidity through Saturday.

 - Humidity returns Sunday along with daily diurnal storm chances
   into next week.

&&

.DISCUSSION...
Issued at 1200 PM CDT Fri Sep 18 2026

Satellite derived PW depicts quite the moisture gradient across
Southeast Texas. As of early this afternoon, areas west of I-45
remain with PW values closer to the 75th percentile (~1.80") whereas
much drier air near or below the 25th percentile (~1.18") moves in
from the east and is currently enveloping areas near and east of I-
45. Your first question (other than how long it`ll last...we`ll get
to that) is probably what impacts will this have on the forecast.
Rain chances won`t completely go away for areas near Matagorda Bay
today where we`ve already seen spotty showers earlier this morning.
Lingering moisture down there will keep isolated showers in the
forecast through the early afternoon. High temperatures will still
top out in the 90s, but it`ll be a drier heat out east versus the
typical humid heat out west. All of us will get the dry heat
Saturday though! The main impact of this drier air will be felt
overnight.

Drier air cools more efficiently, so low temperatures (outside of
urban and coastal areas) will range from the upper 60s to the low
70s. Upper 60s was not a typo! It won`t be a fall-type of feel, but
it`s the closest we can get for now. Areas around the Houston metro
area and along the coast will only bottom out in the mid 70s to low
80s, so we`ll have to wait a little bit longer to see near normal
low temperatures (low 70s). This did make me wonder when was the
last time Houston was below 70 degrees (we won`t get below 70
tonight, so don`t get excited). The last time we were below 70
degrees was 113 days ago on May 28th. The autumnal equinox is coming
up on Tuesday the 22nd, so there is a light at the end of the
tunnel...but that light extends past this forecast period.

Drier air also heats up efficiently and with PW values remaining
near the 25th percentiles on Saturday, expect high temperatures
mainly in the mid to upper 90s. Can`t entirely rule out some mid
morning to early afternoon showers along the coast. Low-level
moisture increases on Sunday with a ridge axis sliding in and a
developing mid-level high (heatdome) developing overhead around
midweek. This means hot and humid conditions will be back on the
menu along with daily chances for isolated showers/storms mainly
south of I-10 along the seabreeze. I do want to address that some
deterministic guidance is showing the potential for a backdoor cold
front around Wednesday/Thursday. It`s too early to lock in one
solution over another, but I can say that even if the front manages
to push through it wouldn`t be a drastic change in temperatures
based on what we`re seeing in the ensemble guidance. Take a peek at
the forecast for low temperatures after Wednesday and you`ll see
what I mean.

Long story short: even though we`re on the cusp of astronomical
fall, the hot and humid pattern continues to hold on after our brief
period of drier conditions.

Batiste

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1200 PM CDT Fri Sep 18 2026

VFR conditions will prevail during this TAF cycle. E winds today
will become calm and VRB overnight, and then turn SE next morning.
MVFR cigs/vis are possible at CXO during the overnight/early morning
period, so model trends will continue to be monitored.

JMG

&&

.MARINE...
Issued at 1200 PM CDT Fri Sep 18 2026

Light to occasionally moderate easterly winds continue to persist
today. Expect these winds to transition to southeasterly by Saturday
night. Onshore flow will prevail through early next week, then
easterly winds make a return around midweek. Daily chances for
isolated to scattered showers and storms continue mainly in the
overnight to morning hours offshore and late morning to afternoon
near the bays.

Batiste

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  72  98  73  97 /   0   0   0   0
Houston (IAH)  75  95  76  96 /   0   0   0  20
Galveston (GLS)  83  90  83  90 /   0  10  20  10

&&

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

$$

DISCUSSION...Batiste
AVIATION...JMG
MARINE...Batiste

NWS HGX Office Area Forecast Discussion