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National Weather Service Forecast Discussion

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716
FXUS64 KHGX 311035
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
435 AM CST Wed Dec 31 2025

...New AVIATION...

.KEY MESSAGES...

- Freezing temperatures are expected for much of the area
  overnight into Wednesday morning, with forecast lows of 28-32
  for most locations not in the urban core of Houston or the
  immediate coast.

- Hard freeze potential is virtually nil for most of the area.
  However, there is a low chance of a hard freeze (25 percent or
  less) in the northernmost reaches of the area near the Trinity
  River north of Lake Livingston. For those with critical
  vulnerability to a hard freeze, preparation against that may be
  a good idea despite the lower probability of it occurring.

- Abnormally low water levels in Galveston Bay will continue
  through at least Thursday`s low tide cycle. Continued low water
  is likely due to the very low astronomical tides occurring.

&&

.DISCUSSION...
Issued at 1142 PM CST Tue Dec 30 2025

Last night was a chilly one for sure, dropping all the way to 28
degrees at Crockett. But...things also didn`t end up quite as
chilly as anticipated. While Crockett dipped below freezing,
neither College Station, Bryan, nor Huntsville did, all bottoming
out at 33 degrees - though surely, localized cold spots in the
vicinity of these locations did reach the freezing mark.

Tonight should still be the coldest night of the week. Winds have
gone nearly calm, except for right on the Gulf or actually on the
Gulf (hey there, elevated oil platforms!). This will help to
maximize radiational cooling. For much of the area, the clear sky
will also help. However, this is not as surefire a bet as it may
have appeared last night. There is a cirrus deck, mostly missing
us to the southwest, but is clipping the westernmost portions of
our area. A cloud deck at 25,000 feet will not make nearly as
much of a difference in radiational cooling as one at, say 2,500
or 250 feet would...but, for those where a degree or two means the
difference between a near-freeze and a light freeze? Maybe?

For this particular outcome, I`m mostly looking at the rural
areas southwest of the Houston metro, and south of I-10. This area
was expected to see lows right around/just below freezing, and
this may put that in jeopardy. However, given the situation, it
would almost certainly pay to be prepared for a light freeze and
not get it than the reverse. NBM probabilities of freezing temps
overnight are still in the 60-80 percent range, which is quite
high. Though the HREF is telling a much different story, with a
probability of freezing temps in its ensemble in the 10-20 percent
range. Reality? I suspect somewhere in between, and probably
closer to the NBM. HREF is a small ensemble of only 10 members,
some of which are the same model time-lagged, though it does have
the benefit of being run more frequently. However, I`d worry about
dispersiveness issues here, and would use the big drop in
probability from its output as a reason to hedge downward against
the NBM rather than jump to the HREF outright. My estimated
probability for a light freeze here would be more of a medium
chance, in the 40-60 percent range.

Farther north, there`s much more confidence in reaching the
freezing mark, even if there is a thin cirrus veil. Those in the
Brazos Valley that didn`t see a freeze last night should manage
to dip below the freezing mark by a small margin even in spite of
some cloud cover. Farther north, I`d also expect that freezing
line to come down, and still have lows of 32 edging in on the
Houston metro on the north and west, with Tomball and Katy getting
down to 32. This is a bit warmer than I had in the forecast
yesterday, as last night`s underperformance does have me wary of
getting quite so aggressive with cooling tonight. Still, NBM
probabilities for places north of the metro that did not freeze
last night is still in the 50-70 percent range, clearly more
likely than not. The places that remain safe from freezing temps
are the Houston core and coastal locations, where freezing
probabilities are 20 percent or less (and that 15-20 percent is
really just the Northside and inside the Loop, while those at the
Gulf are virtually nil).

Beyond the light freeze, I did bring up the low potential for a
hard freeze. Guidance has tended to rule this out more as
confidence in a broad light freeze across much of the area
continues to increase. That said, a brief hard freeze can`t be
completely ruled out in our far north - pretty much for those near
the Trinity River upstream of Lake Livingston. NBM hard freeze
probabilities there are still in the 20-30 percent range.
Unlikely, but can`t dismiss it entirely, either. There is also a
small 5-15 percent bullseye in the Trinity Valley downstream of
Lake Livingston, but this is where we`re getting to potential too
low to be worth serious mention.

After tonight, things well, they get rather dull from a
meteorological standpoint. Though after prolonged fog events,
record heat, and gales...I personally am quite ready for something
a little more dull for a change. Weak ridging sets up for most of
the rest of the week, southwest winds set up, and we will warm our
way right back to normal to close 2025, and back up into well
above-average heat to begin 2026. We are likely to see highs above
80 for most everyone west of the Brazos on Friday and even
extending into the Houston metro, where NBM probabilities of
eclipsing that 80 degree mark are above 90 percent. That may be a
bit overstated, but the high likelihood should be true regardless.

For the weekend, things should cool down slightly in the wake of a
weak Pacific cold front moving through, boosted by some phasing
with an upper trough in the northern stream. Still, this is just
going to be enough to take an edge off the heat and back us away
from racing up on record highs again, the forecast is still for
above-average heat to continue through the weekend. With all this
heat and humidity, we will need to keep an eye on the potential
for sea fog again before that front arrives, especially with our
newly cooled coastal waters. However, southwesterly winds are
generally a poor sea fog fetch, so that will be something to chew
on in the days to come, and will not speak with too much certainty
on this just yet. We have enough confidence to put some patchy fog
in the forecast Friday night, but go no further.

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 435 AM CST Wed Dec 31 2025

VFR conditions prevail with winds becoming southwesterly to
south-southwesterly around 5-7 kt later this morning, then
becoming light and variable again this evening.

Batiste

&&

.MARINE...
Issued at 1142 PM CST Tue Dec 30 2025

Wind and sea conditions continue to improve as high pressure
settles into region. On Galveston Bay, however, the low water
situation is not improving as we head into a stretch of very low
astronomical tides. The low water advisory has been extended
through Thursday, and may need to continue even later. Indeed, the
decreasing astronomical tides may eventually even require a low
water advisory for upper portions of Matagorda Bay, though
confidence in this scenario is lower than on Galveston Bay.

Light and variable winds tonight will gradually become more
southwesterly through Wednesday, continuing through Friday.
Eventually, humidity will increase enough that patchy fog will be
possible during the overnight hours Thursday night and Friday
night, but there is still considerable uncertainty in how
significant fog development will be. The southwesterly fetch is
generally a poor one for sea fog development, but this recent cold
blast has cooled the bays and nearshore waters considerably. The
details will continue to be refined through the week on what the
intensity of any fog development may be.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  67  41  73  59 /   0   0   0   0
Houston (IAH)  66  42  73  61 /   0   0   0   0
Galveston (GLS)  61  51  69  64 /   0   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Low Water Advisory until 6 PM CST Thursday for GMZ335.

&&

$$

DISCUSSION...Luchs
AVIATION...Batiste
MARINE...Luchs

NWS HGX Office Area Forecast Discussion