textproduct: Austin/San Antonio

KEY MESSAGES

- Dense fog possible for the Coastal Plains and areas mainly east of I-35 corridor this morning.

- Dry and unseasonably warm weather for Christmas week.

UPDATE

Issued at 917 AM CST Sun Dec 21 2025

We let the Dense Fog Advisory expired at 9 AM CST since visibilities are above critical levels. Otherwise, the forecast for the rest of today is on track as the cold front continues to push over the Coastal Plains and then into the middle Texas coast this afternoon. A bit cooler today with highs in the 60s over the Hill Country and 70s for the remainder of the local area.

SHORT TERM

(Today through Monday) Issued at 1203 AM CST Sun Dec 21 2025

As of midnight Sunday morning, a weak cold front was moving south across the Hill Country and southern Edwards Plateau. Expect this front to continue southward across the remainder of South-Central Texas by noon. Morning lows behind the front should dip into the 40s primarily west of I-35. Ahead of the front, pooling moisture is generating cloudiness across most of the Coastal Plains and portions of the I-35 corridor, with fog developing where moisture convergence is maximized. Modeled near-surface moisture profiles and visibilities are supportive of fog continuing through the early morning before being thinning out and being pushed south and east by the front, with fog clearing the I-35 corridor first and lingering longer over the Coastal Plains. The fog may be locally dense at times, so a Dense Fog Advisory has been issued for portions of the I- 35 corridor (in effect through 6 AM CST) and Coastal Plains (in effect through 9 AM CST), with the timing based on the expected arrival of the front.

The fog should clear out by the afternoon. The high-resolution models have come into better agreement that a weak and localized area of low pressure will drift southwest near I-35 or US-77 during the day. Low-level moisture drawn towards this system just above the surface (primarily below 925mb) should contribute to some persistent cloudiness over the Coastal Plains and the Austin area as clouds wrap around the low-pressure system. These clouds and weak advection are forecast to keep highs today in the 60s and low 70s over the northeastern half of the CWA. If the cloud cover is more robust, a few locations could stay in the 50s for most of Sunday. Over the Rio Grande Plains, sunnier skies and effective boundary layer mixing should keep highs in the upper 70s to around 80.

A moistening trend returns Monday night with resurgent southerly low- level flow, with another opportunity for fog across portions of South-Central Texas Monday morning. Highs Monday are forecast to be generally in the 70s.

LONG TERM

(Monday night through Saturday) Issued at 1203 AM CST Sun Dec 21 2025

Warm southerly flow will be in full swing by Tuesday as an anomalously strong upper-level ridge settles over Texas, maintaining unseasonably warm temperatures throughout the week. Ensembles are in virtually unanimous agreement that the ridge ridge (with 500mb heights of 588-590 dm) could be among the strongest observed over our area for this time of year. Highs will likely remain in the upper 70s to low 80s with mild overnight lows in the upper 50s to low 60s. Those values are about 10 to 20 degrees higher than the normal for late December. Dew points will also remain unseasonably muggy as flow off the Gulf continues. There is little indication that this warm weather pattern will change during the workweek as the jet stream remains flexed well to the north. A few of the medium- range deterministic models suggest an occasional light shower could sneak into the area as the ridge occasionally varies in strength over the week, but chances are very low and kept out of the forecast.

AVIATION

(12Z TAFS) Issued at 646 AM CST Sun Dec 21 2025

Low clouds and fog will clear KSSF around 13Z as northwesterly winds and drier air move in behind a cold front. Stratus deck over central Texas is noted and based on satellite trends and hi-res guidance, we have added a period of MVFR cigs to KAUS between 16-22Z today.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 71 54 74 63 / 0 0 0 0 Austin Bergstrom Intl Airport 70 52 75 63 / 0 0 0 0 New Braunfels Muni Airport 73 52 74 61 / 0 0 0 0 Burnet Muni Airport 67 48 74 61 / 0 0 0 0 Del Rio Intl Airport 76 48 76 58 / 0 0 0 0 Georgetown Muni Airport 67 52 76 62 / 0 0 0 0 Hondo Muni Airport 77 49 75 61 / 0 0 0 0 San Marcos Muni Airport 73 51 75 62 / 0 0 0 0 La Grange - Fayette Regional 73 55 76 63 / 0 0 0 0 San Antonio Intl Airport 74 53 74 63 / 0 0 0 0 Stinson Muni Airport 76 54 76 64 / 0 0 0 0

EWX WATCHES/WARNINGS/ADVISORIES

None.