The core of a modified arctic air mass settled over all of South Texas on the morning of February 11th, providing clear skies and light winds.  Cool dry air, with afternoon high temperatures only in the 50s on the 10th, allowed temperatures to tumble after sunset, eventually bottoming out in the 20s in most areas, except upper teens in preferred colder spots of the Brush Country, and just above freezing near the Cameron County coast, where easterly winds arrived prior to daybreak.
Following this freeze, temperatures would soon rise above average by mid month, and remain warm through the 28th.

Frost/Freeze in JIM HOGG, TEXAS
From 10-FEB-11 11:15:00 to 11-FEB-11 08:15:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Temperatures fell to 32F or slightly below before midnight on the 11th, then continued to steadily drop, reaching down to 20 or the lower 20s in most areas of the county. At least nine hours of freezing temperatures were recorded, though up to 12 hours may have occurred in colder pockets.  The low temperature at Jim Hogg County Airport northwest of Hebbronville was 24 degrees just after sunrise, with hard freeze conditions (less than 28 degrees) lasting for a total of 2.5 hours.

Frost/Freeze in ZAPATA, TEXAS
From 11-FEB-11 00:00:00 to 11-FEB-11 08:30:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Temperatures fell to 32F or slightly around midnight on the 11th, then continued to steadily drop, reaching down to 20 to the lower 20s in most areas of the county. At least eight hours of freezing temperatures were recorded, though up to 12 hours may have occurred in colder pockets.  The low temperature at Zapata County Airport in Medina was 20 degrees, with 5 hours of hard freeze conditions (less than 28 degrees).  The Falcon Lake Remote Automated Weather Station just south of the Zapata Starr county line was 22, with hard freeze conditions lasting for a total of 7 hours.

Frost/Freeze in HIDALGO, TEXAS
From 11-FEB-11 01:00:00 to 11-FEB-11 08:00:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Temperatures fell to 32F around or just after midnight on the 11th, then continued to steadily drop, reaching down to the upper 20s in most areas of the county. For most suburban and rural areas, 7 hours of freezing temperatures were recorded, though up to 11 hours were recorded in colder pockets.  In urban areas, 2 to 4 hours of freezing temperatures were recorded.
The following minimum temperatures were recorded:  McAllen/Miller Airport (29 degrees, 3 hours freezing); Edinburg Int'l Airport (28 degrees, 7 hours freezing); Weslaco/Mid Valley Airport (30 degrees, 3 hours); Linn/San Manuel Remote Automated Weather Station (23 degrees, 10.5 hours freezing, 10 hours hard freeze below 28 degrees), and Santa Ana/Lower RGV National Wildlife Refuge (25 degrees, 9 hours freezing, 6 hours hard freeze).

Frost/Freeze in KENEDY, TEXAS
From 11-FEB-11 00:00:00 to 11-FEB-11 08:30:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures were estimated to have fallen to 32F or slightly lower by midnight on the 11th, then continued to steadily drop, reaching the lower and mid 20s across teh King Ranch by daybreak.  At least eight hours of freezing temperatures were recorded, though up to 10 hours may have occurred in colder pockets.  The minimum temperatures at both Lebh Shomea House of Prayer, 7 miles east of Sarita, and Armstrong, reached 24 degrees just after sunrise.  Hard freeze conditions (less than 28 degrees) likely lasted for 5 to 7 hours, perhaps longer in other sheltered locations along the Brooks/Kenedy County line.

Frost/Freeze in CAMERON, TEXAS
From 11-FEB-11 01:00:00 to 11-FEB-11 08:00:00 (CST-6)
Property damage: 0.00K
Reported by: ASOS

Temperatures dropped to 32F shortly after midnight on the 11th, and fell a few degrees further by sunrise, bottoming out at 28F at Harlingen/Valley International Airport before rising above freezing just before 8 AM.  The long duration freezing temperatures were likely confined to rural and typically colder areas covering the north and west half of the county; Brownsville/South Padre Island Int'l Airport only fell to 36F, a likely combination of low level mixing of northerly winds with veering winds off the surface from the warmer Gulf of Mexico.

Frost/Freeze in WILLACY, TEXAS
From 11-FEB-11 01:00:00 to 11-FEB-11 08:00:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures dropped to 32F shortly after midnight on the 11th, and fell a few degrees further by sunrise, bottoming out at 27F at Raymondville shortly after sunrise.  Typically colder locations west of Lyford and Raymondville may have had several hours of a hard freeze - temperatures below 28 degrees, along with up to 10 hours of freezing temperatures overall.  The Remote Automated Weather Station at Linn/San Manuel, 8 miles west of the Willacy/Hidalgo County line, recorded a minimum temperature of 23 degrees with 10 hours of a hard freeze - or temperatures below 28 degrees.

Frost/Freeze in BROOKS, TEXAS
From 11-FEB-11 00:00:00 to 11-FEB-11 08:30:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures fell to 32F or slightly below by midnight on the 11th, then continued to steadily drop, reaching the upper teens in colder pockets, including the Hollywood Hunting Camp west of Falfurrias, by daybreak.  At least eight hours of freezing temperatures were recorded, though up to 12 hours may have occurred in colder pockets.  The low temperature at Brooks County Airport was 28 degrees just after sunrise; the low temperature at the Linn/San Manuel Remote Automated Weather Station was 24 degrees, with hard freeze conditions (less than 28 degrees) lasting for 10 hours.

Frost/Freeze in STARR, TEXAS
From 11-FEB-11 00:00:00 to 11-FEB-11 08:30:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures fell to 32F or slightly lower around midnight on the 11th, then continued to steadily drop, reaching down to the lower and mid 20s in most areas of the county. At least eight hours of freezing temperatures were recorded, though up to 12 hours may have occurred in colder pockets.  The low temperature at the Falcon Lake Remote Automated Weather Station just south of the Zapata Starr county line was 22, with hard freeze conditions (less than 28 degrees) lasting for a total of 7 hours.  The low temperature at Rio Grande City (cooperative observer) was 25 degrees.