textproduct: Houston/Galveston

KEY MESSAGES

- Dangerously hot conditions expected today. A Heat Advisory is now in effect for Harris County for heat indices between 105-110F (41- 43C).

- Isolated showers/thunderstorms are possible today and on Sunday. Chance of isolated to scattered sea breeze showers/storms increases early next week.

DISCUSSION

Issued at 1232 AM CDT Sat Jul 4 2026

The dominant mid-level ridge that setup across the eastern U.S over the last several days has begun to slowly break down. As the atmosphere reshuffles from the massive ridge, mid-level heights look to briefly increase across our region this weekend. This will help promote slightly drier and slightly warmer conditions across the area. Currently, quiet weather conditions is seen across our area. Winds are generally light at 5 mph out of the south.

The biggest change with this forecast package was the issuance of a Heat Advisory for inland and coastal Harris County. A combination of slightly higher temperatures and lower shower/thunderstorm coverage placed a majority of Harris County in a range of max heat indices between 107-109F (42-43C). With several events ongoing today and greater than fifty percent of the county exceeding Heat Advisory Criteria, it was prudent that a Heat Advisory was issued. Heat indices of 108F (43C) or higher will be more isolated in occurrence outside of Harris County and thus a Heat Advisory was not considered elsewhere. Heat indices look to remain just under the 108F threshold on Sunday as well, although it could be close once again in Harris County. A brief decrease in maximum temperatures will be possible on Monday and Tuesday as ridging relaxes some. However, maximum heat indices look to remain elevated as increased moisture moves into the region. Tuesday in particular could be close to reaching Heat Advisory criteria depending on shower/thunderstorm coverage in the afternoon. Guidance shows ridging building back into the region towards the latter half of next week, which will keep the heat threat around for the foreseeable future.

Isolated seabreeze showers/thunderstorms will continue today and Sunday, but slightly drier conditions should limit coverage compared to the past couple of days. Models show a mid to upper- level impulse swing down the eastern Southern Plains early next week. This will help lower mid-level heights Monday and Tuesday. It remains unlikely that we will see any direct effects from the mid to upper-level impulse, but it should allow for an increase in seabreeze showers/thunderstorms each afternoon. Ran chances look to diminish once again towards the latter half of next week.

AVIATION

(12Z TAF Issuance) Issued at 606 AM CDT Sat Jul 4 2026

Patchy fog has been developing over the last hour or so. This will lead to brief MVFR vis through 13/14Z. Otherwise, VFR conditions will prevail through this TAF cycle. Recent CAMs hint at very isolated convection late this morning through the afternoon. With confidence being low in coverage, have opted to leave any mention of TS out of the TAFs with this update. Winds will remain light, 5-10 knots, through this TAF cycle.

MARINE

Issued at 1232 AM CDT Sat Jul 4 2026

Light onshore flow will continue over the next several days. Gulf seas are expected to average 1 to 3 feet. Isolated coastal and Gulf showers will be possible each morning, with a chance of isolated thunderstorms along the sea breeze in the afternoon. By the middle to later part of next week, a gradually steepening pressure gradient may allow for an increase in south to southeast winds, along with a corresponding increase in the seas. For now, the forecast shows onshore winds increasing to 10-15 knots by Tuesday/Wednesday, before increasing further to the 15-20 knot range by Thursday. Seas may increase to 3-4 feet by week's end.

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 96 77 95 77 / 10 0 0 0 Houston (IAH) 97 79 96 79 / 20 10 10 0 Galveston (GLS) 90 83 90 83 / 10 0 0 0

HGX WATCHES/WARNINGS/ADVISORIES

TX...Heat Advisory from 11 AM this morning to 7 PM CDT this evening for TXZ213-313.

GM...None.