The National Weather Service has issued a Freeze Warning for the second night in a row for much of the KXAN viewing area. This warning includes all of the Austin metro area in Williamson, Travis and Hays counties, and Burnet, Gillespie, Blanco, Bastrop and Lee counties. The warning is effective from 3 a.m. to 9 a.m. Wednesday morning.

Even though the warning does not officially include much of the Hill Country, that is only because most of those areas have already experienced their first freeze of the season. Temperatures will fall below freezing again tonight across almost all of the Hill Country.

Clouds increased across Central Texas early Tuesday morning, keeping temperatures just above freezing in many areas, but there were also many areas where readings did fall to 32 or below. The coldest temperatures were recorded in the Hill Country, where a couple of low lying locations in Llano and San Saba counties dropped to 25 degrees.

Tonight, the clouds are expected to slowly clear from the west, which will allow very efficient radiational cooling, resulting in an extended period of freezing temperatures in the coldest locations—possibly 9 hours or so. Elsewhere, temperatures are expected to be below freezing for an average of 2-6 hours.

Cover sensitive plants to prevent or limit damage.

Here are the details from the National Weather Service:

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
322 PM CST TUE NOV 13 2012

...A FREEZE WARNING IS IN EFFECT FOR TONIGHT ACROSS PORTIONS
OF SOUTH CENTRAL TEXAS AND THE HILL COUNTRY...

.COOL AND DRY CONDITIONS WILL SETTLE OVER SOUTH CENTRAL TEXAS
TONIGHT. A RAIN MAKING WEATHER SYSTEM OVER THE AREA THIS
AFTERNOON IS FORECAST TO MOVE EAST THIS EVENING THROUGH
TONIGHT.  SKIES ARE EXPECTED TO SLOWLY CLEAR FROM THE
WEST AND NORTHWEST TONIGHT. WITH LESS CLOUD COVER LATER
TONIGHT AND EARLY WEDNESDAY MORNING...LOWS NEAR FREEZING
ARE POSSIBLE OVER THE HILL COUNTRY TO ADJACENT PARTS OF
CENTRAL TEXAS. LOWS NEAR FREEZING ARE ALSO EXPECTED FOR
LLANO COUNTY...HOWEVER SINCE A FREEZE HAS ALL READY BEEN
OBSERVED OVER LLANO COUNTY ON OCTOBER 29TH AND THIS MORNING...
THE FREEZE WARNING IS NOT IN EFFECT FOR LLANO COUNTY. THE
FREEZE WARNING IS IN EFFECT FOR BURNET...WILLIAMSON...REAL...
KERR...BANDERA...GILLESPIE...KENDALL...BLANCO...HAYS...
TRAVIS...BASTROP...AND LEE COUNTIES...WHERE WIDESPREAD FREEZING
TEMPERATURES HAVE NOT BEEN OBSERVED SO FAR THIS FALL.
THE FREEZING TEMPERATURES ARE EXPECTED TO BE MAINLY IN THE
UPPER 20S TO NEAR FREEZING AND LAST FROM TWO TO SIX HOURS.

TXZ172-173-185>194-141000-
/O.NEW.KEWX.FZ.W.0002.121114T0900Z-121114T1500Z/
BURNET-WILLIAMSON-REAL-KERR-BANDERA-GILLESPIE-KENDALL-BLANCO-HAYS-
TRAVIS-BASTROP-LEE-
INCLUDING THE CITIES OF...BURNET...GEORGETOWN...LEAKEY...
KERRVILLE...BANDERA...FREDERICKSBURG...BOERNE...BLANCO...
SAN MARCOS...AUSTIN...BASTROP...GIDDINGS
322 PM CST TUE NOV 13 2012

...FREEZE WARNING IN EFFECT FROM 3 AM TO 9 AM CST WEDNESDAY...

THE NATIONAL WEATHER SERVICE IN AUSTIN/SAN ANTONIO HAS ISSUED A
FREEZE WARNING...WHICH IS IN EFFECT FROM 3 AM TO 9 AM CST
WEDNESDAY.

* TEMPERATURE...EARLY MORNING LOWS OF 28 TO 32 DEGREES.

* IMPACTS...A LIGHT FREEZE MAY DAMAGE OR KILL TENDER VEGETATION.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FREEZE WARNING MEANS SUB-FREEZING TEMPERATURES ARE IMMINENT OR
HIGHLY LIKELY. COVER SENSITIVE PLANTS TO PREVENT OR LIMIT DAMAGE.