A large dome of Arctic High Pressure spread from the Great Plains southward into Deep South Texas and well into Mexico beginning late on February 1st and continuing into Groundhog Day, February 2nd 2011. Strong northwest winds turned what had been a balmy afternoon February 1st into a dangerously cold morning for unprotected people, pets, and plants on the 2nd. Freezing temperatures arrived in the Brush Country and King Ranch soon after midnight, and drove through the Rio Grande Valley before daybreak.  Steely gray stratus behind the front kept temperatures from rising much above 32 degrees through the day .
The combination of northwest winds 20 to 25 mph and gusty near the coast, and 15 to 20 mph and gusty inland, dropped feels like temperatures into the low to mid teens in time for the morning school bus. The change from Tuesday afternoon to Wednesday morning was more than 40��F in air temperature, but a whopping 50 to 60�� lower in how it actually felt ��� quite a shock to most residents of the Rio Grande Valley.
Dangerous wind chills held in the teens to lower 20s for the remainder of the daylight hours, one of the coldest feeling days in decades. A number of locations had temperatures drop to or below the freezing point (32��F) for several hours; a brief hard freeze occurred across the northern tier of the brush country and King Ranch.

Frost/Freeze in CAMERON, TEXAS
From 02-FEB-11 05:00:00 to 02-FEB-11 11:00:00 (CST-6)
Property damage: 0.00K
Reported by: ASOS

Temperatures fell to 32 degrees at around 5 AM on February 2nd in Harlingen and Bayview, then continued falling to 30 or 31 degrees for several hours after sunrise before slowly rising back above freezing at around noon.  Duration of freeze varied across the county; temperatures only touched 32 at the Brownsville/South Padre International Airport by mid morning, but remained at or below 32 at the Laguna Atascosa National Wildlife Refuge for nearly 8 hours (530 AM until 130 PM), bottoming out at 30 degrees a little after 9 AM CST.

Frost/Freeze in COASTAL CAMERON, TEXAS
From 02-FEB-11 05:00:00 to 02-FEB-11 12:00:00 (CST-6)
Property damage: 0.00K
Reported by: ASOS

Temperatures fell to 32 degrees at around 5 AM on February 2nd in Harlingen and Bayview, then continued falling to 30 or 31 degrees for several hours after sunrise before slowly rising back above freezing at around noon.  Duration of freeze varied across the county; temperatures only touched 32 at the Brownsville/South Padre International Airport by mid morning, but remained at or below 32 at the Laguna Atascosa National Wildlife Refuge for nearly 8 hours (530 AM until 130 PM), bottoming out at 30 degrees a little after 9 AM CST.
Temperatures on South Padre Island flirted with 32 degrees thorugh much of the afternoon on the 2nd, but largely remained a hair above freezing.

Frost/Freeze in ZAPATA, TEXAS
From 02-FEB-11 03:15:00 to 02-FEB-11 12:45:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

The Automated Weather Observing System at Zapata/Medina Airport dipped to 32 degrees a little after 3 AM on the 2nd, bottoming out at 30 degrees during the mid morning hours before rising above freezing for a few hours during the afternoon.  Eight hours of freezing temperatures were recorded at the Falcon Lake Remote Automated Observing System near the Starr/Zapata line, with a low of 31 degrees there and at Falcon Dam, also near the Starr/Zapata line.

Frost/Freeze in STARR, TEXAS
From 02-FEB-11 03:15:00 to 02-FEB-11 12:45:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Eight hours of freezing temperatures were recorded at the Falcon Lake Remote Automated Observing System near the Starr/Zapata line, with a low of 31 degrees there and at Falcon Dam, also near the Starr/Zapata line.
The cooperative observer at Rio Grande City dropped to 32 degrees for an unknown period of time during the morning of the 2nd.  Time duration of the freeze was interpolated between Zapata (west) and Jim Hogg (north) Counties, and the fact that Starr County has a lower population than Hidalgo County to the east.

Frost/Freeze in KENEDY, TEXAS
From 02-FEB-11 02:30:00 to 02-FEB-11 12:30:00 (CST-6)
Property damage: 0.00K
Reported by: ASOS

Temperatures fell to 32 degrees shortly after 2 AM on February 2nd in Falfurrias (Brooks County), with similar conditions likely occurring due east across the King Ranch. Temperatures continue to drop, reaching the upper 20s to around 30 from north to south during the mid morning hours, before slowly rising back above freezing by early afternoon.  Between 7 and 10 hours of freezing temperatures were estimated in the county before readings rose a few degrees above freezing for the afternoon and evening.  Low temperature at the Lebh Shomeah retreat east of Sarita was 26 degrees, mid morning of the 2nd.

Frost/Freeze in WILLACY, TEXAS
From 02-FEB-11 04:00:00 to 02-FEB-11 12:00:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures were estimated to have fallen to 32 degrees at around 4 AM on February 2nd in and near Raymondville, then continued falling to 30 degrees for several hours after sunrise before slowly rising back above freezing at noon or shortly thereafter.

Frost/Freeze in COASTAL WILLACY, TEXAS
From 02-FEB-11 04:00:00 to 02-FEB-11 12:00:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures were estimated to have fallen to 32 degrees at around 4 AM on February 2nd in and near Port Mansfield, then continued falling to 30 degrees for several hours after sunrise before slowly rising back above freezing at noon or shortly thereafter.

Frost/Freeze in HIDALGO, TEXAS
From 02-FEB-11 06:15:00 to 02-FEB-11 11:15:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Temperatures fell to 32 degrees between 5 and 7 AM on February 2nd across Hidalgo County, with readings hovering near the freezing point until mid morning to around noon in different locations in the county under a steely gray overcast.  How long the freezing temperatures lasted varied from station to station.  McAllen/Miller airport fell to 32 for less than an hour; Edinburg International Airport for one and one half hours.  Meanwhile, the Lower Rio Grande Valley National Wildlife Refuge (NWR) at San Manuel had 8 hours of freezing temperatures, and the NWR at Santa Ana along the Rio Grande had 5 hours of freezing.  Lows ranged from 30 to 32 degrees countywide.

Frost/Freeze in JIM HOGG, TEXAS
From 01-FEB-11 23:15:00 to 04-FEB-11 11:15:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Across the northern third of Jim Hogg County, temperatures fell to 32 degrees just before midnight on February 2nd, and would not rise above 32 until 11 AM on the 4th - a total of 60 hours straight with temperatures below freezing!  Readings remained around or just below 32 through the 2nd under a steely gray sky.  Values would dip into the mid and upper 20s each morning (2nd and 3rd) but only rise to 31 degrees on the 3rd as a misty freezing rain spread westward across the area.  Temperatures would fall back into the upper 20s during the evening of the 3rd, then drop quickly to the lower 20s as the precipitation quickly moved east and skies cleared early on the 4th.  Ample sunshine on the 4th would finally push temperatures above 32 just before noon on the 4th.

Frost/Freeze in BROOKS, TEXAS
From 02-FEB-11 02:30:00 to 02-FEB-11 12:15:00 (CST-6)
Property damage: 0.00K
Reported by: ASOS

Temperatures fell to 32 degrees shortly after 2 AM on February 2nd in Falfurrias, then continued falling to 30 degrees for several hours after sunrise before slowly rising back above freezing by early afternoon.  Between 7 and 10 hours of freezing temperatures were reported/estimated in the county before readings rose a few degrees above freezing for the afternoon and evening.