textproduct: Houston/Galveston

KEY MESSAGES

- Dangerous heat will continue through the weekend, with heat indices in the 108 to 110 range. Limited cooling overnight will exacerbate the heat.

- Scattered showers and thunderstorms are possible on Friday and Saturday, with the potential for locally heavy rainfall. There is a Slight Risk (Level 2 out of 4) of Excessive Rainfall Friday and Friday night.

- High risk of strong rip currents is expected through the weekend.

DISCUSSION

Issued at 107 PM CDT Thu Jun 18 2026

Broad upper troughing will persist over much of the CONUS, with ridging building over the Gulf. Strong southerly flow over the local area continues to filter an abundance of moisture across the area. Meanwhile, mostly clear skies have allowed temps to soar into the lower 90s. Temps may climb another degree or two this afternoon. Combined with dewpoints in the upper 70s, RH values are quite moist. Heat indices are already in the Heat Advisory range (108-113) and these should max out around 115 this afternoon. Given this, an Extreme Heat Warning is in effect for the entire area through this evening.

Heat concerns will continue into the weekend, as the moist airmass remains over the area. There will be enough heating each day for temps to rise into the lower 90s. One caveat will be Friday into Saturday, when a southern stream trough tries to move through the area. That said, given the warmer dewpoints, overnight lows will remain in the upper 70s to lower 80s through Saturday night. This will provide little in the way of cooling and the risk for heat illnesses may compound each day. Due to the lower confidence with the trough building in, a Heat Advisory is in effect through Saturday night. If the clouds/rain don't pan out, we may have to explore more Extreme Heat products this weekend.

Turning our attention to the potential rain Friday afternoon into Saturday, guidance is in a bit of a disagreement on where the trough will move and, therefore, where the heavier rain will set up. The moist airmass persists, with PWs well above normal, so there is a potential for locally heavy rainfall. The area remains wet from previous days rain, so any additional heavy rain will quickly become a flooding concern. Low confidence on timing and location, but it's a concern to monitor over the next 24 hours.

Beyond Sunday, we will likely be in a more typical summer pattern, with high pressure building in and little to no rain chances. The deep layer moisture transport may be more limited and reduce the risk of heat.

AVIATION

(00Z TAF Issuance) Issued at 609 PM CDT Thu Jun 18 2026

The hot and humid conditions today has led to the development of some haze, especially south of I-10. LVJ, LBX, and GLS have all been reporting visibility around 4-6mi this afternoon due to this haze, and this will likely continue into this evening. Otherwise VFR conditions this evening will transition to MVFR conditions across much of the region between 3-5z with CIGs dropping to around 1500ft with scattered clouds around 500-700ft. Patchy fog is also possible late tonight into early Friday morning bringing visibility reductions to around 4-6mi. UTS and CXO may see IFR conditions beginning around 08-13z with CIGs down to around 700ft. VFR conditions return to the region by 14-16z with SSE winds around 8-12kt prevailing through the day.

There will be a chance of showers and thunderstorms to develop and move across the region from west to east Friday afternoon into the evening hours. Exact timing and location of the storms is still a bit uncertain, but for now have included a PROB30 for all inland terminals Friday afternoon. These thunderstorms will have the capability of producing gusty winds and heavy rainfall reducing visibility.

Another night of MVFR (to occasionally IFR) conditions is expected Friday night into Saturday morning.

Fowler

MARINE

Issued at 124 PM CDT Wed Jun 17 2026

Light to moderate southerly winds and sea up to 6ft are expected today and persist into the weekend. Caution flags could be warranted at times over the next few days as the pressure gradient tightens.

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 79 93 78 91 / 0 30 50 50 Houston (IAH) 81 93 80 92 / 0 20 30 30 Galveston (GLS) 84 90 83 89 / 0 0 30 10

HGX WATCHES/WARNINGS/ADVISORIES

TX...Extreme Heat Warning until 8 PM CDT this evening for TXZ163-164- 176>179-195>200-210>214-226-227-235>238-300-313-335>338-436- 438-439.

Heat Advisory until 10 PM CDT Saturday for TXZ163-164-176>179- 195>200-210>214-226-227-235>238-300-313-335>338-436>439.

High Rip Current Risk through Friday evening for TXZ436>439.

GM...Small Craft Should Exercise Caution through Friday morning for GMZ330-335.

Small Craft Advisory until 7 AM CDT Friday for GMZ350-355-370- 375.