Travis and surrounding counties have been issued a freeze warning for tonight. From the National Weather Service:

FREEZING TEMPERATURES LATE TONIGHT THROUGH TUESDAY MORNING...

...NORTHERLY WINDS WILL CONTINUE TO DECREASE TODAY AND
SURFACE HIGH PRESSURE WILL BUILD ACROSS SOUTH CENTRAL TEXAS. THE
DRY AIR MASS COMBINED WITH LIGHT WINDS AND CLEAR SKIES OVERNIGHT
WILL RESULT IN TEMPERATURES FALLING BELOW FREEZING. A WIDESPREAD
FREEZE WILL OCCUR ACROSS SOUTH CENTRAL TEXAS WITH A HARD FREEZE
ACROSS THE HILL COUNTRY.

...FREEZE WARNING REMAINS IN EFFECT FROM 11 PM THIS EVENING TO
10 AM CST TUESDAY...

* TIMING...TEMPERATURES WILL DROP BELOW FREEZING AFTER 11 PM
  THIS EVENING AND REMAIN BELOW UNTIL 10 AM TUESDAY.

* TEMPERATURES...LOWS RANGING FROM 17 TO 25 DEGREES ACROSS THE
  HILL COUNTRY. LOWS 25 TO 30 DEGREES ACROSS THE REST OF SOUTH
  CENTRAL TEXAS.

* IMPACTS...SUB-FREEZING TEMPERATURES ARE HIGHLY LIKELY TONIGHT.
  THESE CONDITIONS WILL KILL CROPS AND OTHER SENSITIVE
  VEGETATION AND WILL BE DANGEROUS FOR PETS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FREEZE WARNING MEANS SUB-FREEZING TEMPERATURES ARE IMMINENT OR
HIGHLY LIKELY. THESE CONDITIONS WILL KILL CROPS AND OTHER
SENSITIVE VEGETATION. TAKE ACTION TO PROTECT PLANTS...PETS...
PIPES...AND PEOPLE.