Rio Grande Valley:
A cold front, associated with a surface low in central Texas, will be pushing through the RGV late tonight/early Christmas morning. Highs today reached the lower 80s with southeast winds at 10-15 mph. Tonight should be mostly cloudy to overcast with a chance of showers a head of the front. Lows will continue dropping below 50 as Christmas morning arrives, with gusty winds shifting out of the north and northwest at 15-20 mph. Gusts could reach as high as 25 mph.
Christmas Day: A very chilly Christmas morning is in store. Afternoon highs will reach the mid 60s. Clouds will begin to decrease as the afternoon approaches. Northerly winds will be strong at 15-20 mph, with higher gusts. Mostly clear skies will make evening lows very cold, especially in the northern Valley. Lows will range from the lower 30s, in the upper Valley, to upper 30s, near the coast. Winds will begin to die down a bit at 10 mph.
(12/26): Sunday looks to be mostly clear, with highs in the lower 60s, as the front’s effect really begins to be felt. Winds will be out of the northeast at 5-10 mph. Sunday night will be mostly clear with lows in the lower 40s and northeast winds at 5-10 mph.
(12/27): Another change in store for Monday. Winds will begin shifting out of the east and southeast. This allows lower-level moisture to enter the RGV and raises the dewpoint temperature. In turn, skies will be partly sunny to mostly cloudy. Highs will be in the mid 60s. An upper-level trough allows for Pacific flow and enhances the chance of showers (30%) for Monday evening, Tuesday, and on into Wednesday.