textproduct: Houston/Galveston

KEY MESSAGES

- A light freeze can be expected for at least a portion of the area tonight, with an even broader swath of the area seeing a light freeze Tuesday night.

- Hard freeze potential is virtually nil for most of the area. However, there is a low chance (30 percent of less) of a hard freeze in the northernmost reaches of the area - portions of Madison, Houston, Walker, Trinity, and Polk counties. It may be prudent to consider protections against that occurrence for locations in those areas where vulnerability to a hard freeze is a critical concern. - Hazardous conditions remain on coastal waters while winds and seas slowly improve from the recent gale. A Small Craft Advisory is in place through mid-day Tuesday. Abnormally low water levels in Galveston Bay are also anticipated, and these may persist deeper into the week.

DISCUSSION

Issued at 1227 AM CST Tue Dec 30 2025

There's no fog, I hardly know what to do with myself this evening! Oh right, we've got gusty winds, plummeting temperatures, and...also...*checks notes*...sleet?! Yes, indeed. In an setup that we seem to manage roughly a time or two each winter, we had just enough lingering mid-level moisture to fall out of clouds several thousand feet up - use evaporative cooling falling through the very dry air beneath it to freeze itself, and result in a handful of pellets making it to the ground to ping off of hard surfaces. Fortunately, this happens in amounts far too meager to accomplish anything but light up social media, but it is still frustrating to conclude that the column will be too dry for this potential...only to have it happen anyway. Going forward, cloud bases have now risen to 10-12k feet, and while this SHOULD be high enough to stop any more sleet from reaching the ground, we do still have some radar echoes over the Brazos Valley, so I can't completely rule that out over the next few hours.

Ultimately, though, the main focus of the forecast - and especially the short term portion - is the incoming cold temperatures. Gusty north winds continue, and colder air from the north will keep on getting pumped in tonight. However, the winds will also make the boundary layer more turbulent, which tends to act against cooling, so we've got a bit of cross purposes there. Additionally, while not a pure overcast, we have plenty of clouds overhead to help reduce overnight cooling as well. But with afternoon temps only starting us off from something in the range of 43 to 55 degrees, it won't take much to fall below the freezing mark, especially up in the chillier north.

In my explicit forecast, I have freezing temps focused north of the Houston metro, but that freezing line should be encroaching on the far northern fringes of the metro towards dawn - I'm thinking roughly Caldwell to Conroe to Cleveland northward. But a little bit south of there, we could see localized cold spots as far south as extreme northern and northwest Harris County briefly dip to the freezing mark. This scenario in my head (and my grids) puts the freezing line in roughly the same spot as the line for a 40 percent NBM probability or greater of freezing temps. As I am opting to hedge slightly under NBM, this seems like a reasonable place to draw the line. But for locations south of this line - spots like Brenham, Columbus, Cypress, The Woodlands, etc. NBM has a 20-25 percent chance of a brief, light freeze tonight. Considering chances will be even higher Tuesday night, it probably wouldn't hurt to just be prepped for a light freeze tonight, as well.

Speaking of Tuesday night, it seems like each crack I take at these lows, I'm nudging those numbers down a little more. With high pressure dropping right in, we really are looking to grab a great radiational cooling setup and one chilly night. The urban core of Houston should have a chilly, but above freezing night, though it's definitely worth mentioning that the NBM has freeze probabilities inside the loop as high as 20 percent now. And the less of a concrete jungle you get, the more likely a light freeze will be. Those same NBM probs rise to around 70 percent for Katy, Cypress, and Tomball. And while the highest odds of a freeze stay north of I-10 (roughly over 80 percent), the rural area southwest of the Houston metro is now seeing odds of a freeze as more likely than not all the way down to Lake Jackson! At this point, only the immediate coast and the core of Houston appear safe from that 32 degree temperature between the hours of 3am and 8am Tues night/Wed morning.

For now...I'm opting to hold off on any sort of freeze watch. For most of the area, we've already had our "season ending" freeze warning of the year, and those few locations left are right on the coast, where I'd like to see a little more run-to-run confidence in temps getting this cold before going with a warning there. I will give the day shift one more crack at it tomorrow morning. The one other way we use freeze warnings is for hard freezes. And though a light freeze is virtually certain for the northern part of the area, confidence is also quite high that we won't see a hard freeze. The one area to watch for will be generally north of Huntsville, in portions of Madison, Houston, Walker, Trinity, and Polk counties. There, NBM probabilities for a hard freeze do get into the 20-30 percent range. Probably not high enough for most people to be concerned, but if you have something where protecting against a hard freeze is vitally important, it may be prudent to be prepared anyway, even if the odds favor it not happening.

Beyond a freeze warning, I also gave some consideration to a cold weather advisory. In the northern half of our area, that is when temps or wind chills are expected to get below 20, and below 25 in the southern half of our area. With the gusty winds continuing tonight, wind chills get pretty close to those thresholds, and in the 20s across Southeast Texas. However, temperatures should stay just high enough to keep things above the advisory thresholds, even despite the gusty winds. The reverse is true Tuesday night - yes, it will be the coldest night of the week, but as that is facilitated by the winds dropping off dramatically, neither temps nor wind chills still look to get low enough for a cold weather advisory.

Once we bottom out with the cold, the general trend of the forecast will be for gradual warming and fair weather under the reign of generally high pressure and zonal flow or weak ridging aloft. A passing upper shortwave trough that could probably be well described as a "ripple" should bring no more than some increased cloudiness Thursday into Friday. Winds should remain fairly light, but will turn to be onshore, and jump start the warming trend, such that we are looking for highs to return back to the 70s late in the week. Finally, I had been keen on Saturday as an unexpectedly warm day, with sunny conditions following a weak Pacific front that brings little to no cold air with it. Well...the models have decided - what if that front, but in phase with a trough in the polar jet stream? As those link up, we more solidly get northwest flow aloft instead of westerly flow, so I am begrudgingly holding off on this idea for now, and falling in line with the NBM cooling things down a bit (but still remaining on the warm side of average) going into the weekend.

Now, cross-jet phasing can be a fragile thing, as it can be broken by subtle shifts in either or both troughs. I went to the LREF clustering analysis to see if this was just a passing model fancy, only to be abandoned with the next run. And...it doesn't really seem like it. With the caveat that this type of resolution and ensembling can wipe out subtle features, all four 500 mb clusters in this analysis show a setup that doesn't deviate much from the grand ensemble, and would generally support a slightly cooler day Saturday after the front. Now, because of this setup's fragility, I reserve the right to bring a hot Saturday back to the forecast! But...right now, the data seems to quite clearly favor the model consensus, and so I will follow it for now.

AVIATION

(00Z TAF Issuance) Issued at 526 PM CST Mon Dec 29 2025

Gusty northerly winds should gradually decline this evening into the tonight. The lone exception will be near the coast, where winds may remain gusty until tomorrow morning. Isolated shower activity should subside this evening, as the high VFR cloud deck gradually breaks, yielding to clearer skies tomorrow. Winds tomorrow remain northerly, but will be much lighter than today, averaging around 10 knots.

MARINE

Issued at 1227 AM CST Tue Dec 30 2025

Winds and seas are very slowly diminishing from earlier gale conditions, but this improvement is indeed quite gradual. As a result, winds and seas will stay elevated through Tuesday morning, so a small craft advisory continues for the hazardous conditions lingering on coastal waters.

On the bays, in addition to the high winds and rough waters, currents may become strong near the interface of the rivers and the bays during times of low water, which may particularly be an issue on Galveston Bay. Low water will likely persist through at least Tuesday's low tide cycle and potentially deeper into the week.

Deeper into the week, light northwest winds on Wednesday will become southwesterly by Wednesday night. This light to moderate onshore flow will continue through Friday. The onshore flow will also boost humidity. While we are beyond any model guidance at this point, the expected environment should make patchy fog possible during the overnight hours Thursday night and Friday night. Winds, though, may ultimately create a situation where fog formation is disrupted. This potential will continue to be evaluated through the week.

FIRE WEATHER

Issued at 1227 AM CST Tue Dec 30 2025

Breezy north winds will persist through the night, but more substantially decrease on Tuesday as high pressure settles into the region. While winds may be on their way down, dry conditions will be going nowhere. Very low humidity is virtually certain to persist through Wednesday with minimum relative humidity values dropping into the 20s during the afternoon hours for most of the region. Locations west of the Brazos River will be capable of dropping into the upper teens on Wednesday, boosted by slowly increasing temperatures without a corresponding boost in humidity. The lower winds will mitigate fire weather threats, but it will still be important to consider these dry conditions for fire planning purposes. This will be particularly prudent in areas of dense, fine fuels. Texas A&M Forest Service data shows that in general, near to above normal fuel moisture continues, but grassy areas and other fine fuel beds will be the first to show the influence of a prolonged low humidity stretch.

Later in the week, southwesterly winds will finally lead to increasing humidity Thursday and Friday. This will be interrupted by a weak cold front at the end of the week, roughly around Saturday morning. In the wake of this front, drier conditions will filter back in over the weekend.

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 31 54 30 66 / 0 0 0 0 Houston (IAH) 35 54 33 64 / 0 0 0 0 Galveston (GLS) 39 52 41 60 / 0 0 0 0

HGX WATCHES/WARNINGS/ADVISORIES

TX...None. GM...Small Craft Advisory until noon CST Tuesday for GMZ330-335-350- 355-370-375.

Low Water Advisory until 6 PM CST Tuesday for GMZ335.