textproduct: Houston/Galveston

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

(00Z TAF Issuance) Issued at 505 PM CST Tue Dec 30 2025

Winds only forecast issue here, and that's really stretching the definition of "issue". North winds early this evening will become light/VRB with setting sun, remain that way through the night. Expect them to eventually rise back around/above 5 kts late tomorrow morning, and should be primarily southwesterly when they do so.

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) 32 67 41 73 / 0 0 0 0 Houston (IAH) 34 66 42 73 / 0 0 0 0 Galveston (GLS) 44 61 51 69 / 0 0 0 0

HGX WATCHES/WARNINGS/ADVISORIES

TX...None. GM...Low Water Advisory until 6 PM CST Thursday for GMZ335.