Arctic air continued plunging through Deep South Texas on February 3rd and 4th, returning freezing temperatures to all areas during the late evening of the 2nd or just after midnight on the 3rd.  A weak upper level disturbance combined with just enough low level moisture to develop a mist of freezing drizzle and light freezing rain soon after sunrise on the 3rd across the Lower Valley, spreading west and north through the day.  The precipitation combined with gusty north winds to lock down temperatures at or below 32 degrees for more than 30 hours in all areas.
Overnight on the 3rd and into the 4th, temperatures remained steady from the Lower Rio Grande Valley to the King Ranch, but skies cleared before daybreak farther west, allowing temperatures to bottom out in the lower to mid 20s - a hard freeze.  The combination of gusty north winds 20 to 25 mph mainly east of highway 281 held wind chill temperatures near or below 20 for much of the day on the 3rd, making it the coldest feeling day in more than two decades.

Frost/Freeze in COASTAL CAMERON, TEXAS
From 03-FEB-11 04:00:00 to 04-FEB-11 12:30:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Between 30 and 33 hours of freezing temperatures covered coastal Cameron County, beginning during the pre dawn hours of February 3rd and continuing through around noon on February 4th, after which skies cleared and sunshine warmed temperatures to near 40 degrees.  Through the period, temperatures held generally within a 2 degree range at any one location, between 28 and 32 degrees.
A strong northwest wind drained some of the coldest daytime air in the region onto South Padre Island, where temperatures held between 28 and 29 through the daytime hours on February 3rd, with readings rising toward 30 degrees overnight.

Frost/Freeze in KENEDY, TEXAS
From 02-FEB-11 23:55:00 to 04-FEB-11 10:55:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Air temperatures fell back to 32 degrees just before midnight on February 3rd, and would not recover above 32 until just before noon on February 4th - a total of 33 hours at or below 32 degrees.  The Cooperative observer at the Lebh Shomeah House of Prayer, 7 miles east of Sarita, recorded a low of 26 on the 3rd, with daytime temperatures not exceeding 30 degrees.  The low would dip to 26 again overnight on the 3rd.  Based on proximity to Kingsville, there were several long periods with temperature at or below 27 degrees - a hard freeze. Based on surrounding observations, between 32 and 39 consecutive hours of freezing temperatures occurred.

Frost/Freeze in STARR, TEXAS
From 02-FEB-11 23:00:00 to 04-FEB-11 10:30:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

The Remote Automated Weather Station (RAWS) site at Falcon Lake, in Starr County along the Zapata/Starr County line, recorded a long duration freeze (35.5 hours).  Low temperatures dipped to 26 degrees  with a 14 hour duration of hard freeze on the 4th, when skies cleared for several hours around daybreak.   Temperatures were below 28 degrees for more than 14 hours at this location and the Falcon Lake RAWS also had 14 hours below 28 degrees on the 3rd and 4th, falling below 28 degrees as early as 7 PM on the 3rd.
At Rio Grande City, the cooperative observer dipped to 29 degrees early on the 3rd, only rising to 32 during the daylight hours before falling back to 26 degrees for several hours early on the 4th as skies cleared just prior to daybreak.

Frost/Freeze in BROOKS, TEXAS
From 03-FEB-11 00:55:00 to 04-FEB-11 09:55:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Air temperatures fell back to 32 degrees just after midnight on February 3rd, and would not recover above 32 until just before noon on February 4th - a total of 33 hours at or below 32 degrees.  The Remote Automated Observing site at San Manuel, about 10 miles south of the county line, recorded nearly 35 hours.  Low temperatures at Falfurrias were in the upper 20s on the 3rd and again on the 4th.  A hard freeze - temperatures below 28 degrees for 2 hours or more - was recorded during the early morning hours on the 4th.

Frost/Freeze in ZAPATA, TEXAS
From 02-FEB-11 19:55:00 to 04-FEB-11 10:55:00 (CST-6)
Property damage: 0.00K
Reported by: AWOS

Air temperatures fell back to 32 degrees prior to midnight on February 2nd at the Zapata County (Medina) Airport, and would not recover above 32 until just before noon on February 4th - a total of 39 hours at or below 32 degrees.  The Remote Automated Weather Station (RAWS) site at Falcon Lake, in Starr County along the Zapata/Starr County line, recorded a similar long duration freeze (35.5 hours).  Low temperatures at Zapata County Airport dipped to 26 degrees on the 3rd, and to 22 degrees on the 4th after skies cleared.  Temperatures were below 28 degrees for more than 14 hours at this location and the Falcon Lake RAWS also had 14 hours below 28 degrees on the 4th.  Temperatures were in the mid 20s (26 each morning) at Falcon Lake.

Frost/Freeze in COASTAL WILLACY, TEXAS
From 03-FEB-11 04:00:00 to 04-FEB-11 12:30:00 (CST-6)
Property damage: 0.00K
Reported by: COOP Observer

Between 30 and 33 hours of freezing temperatures covered coastal Willacy County, beginning during the pre dawn hours of February 3rd and continuing through around noon on February 4th, after which skies cleared and sunshine warmed temperatures to near 40 degrees.  Through the period, temperatures held generally within a 2 degree range at any one location, between 28 and 30 degrees.  Hard freezes - defined as 2 or more hours below 28 degrees - did not occur, but there were brief periods where temperatures fell to 27 degrees at Port Mansfield around daybreak each morning.

Frost/Freeze in HIDALGO, TEXAS
From 03-FEB-11 02:00:00 to 04-FEB-11 10:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 5.00M
Reported by: RAWS

Between 30 and 35 hours of freezing temperatures covered Hidalgo County, beginning a little after midnight on February 3rd and continuing through late morning on February 4th after skies clears and sunshine warmed temperatures back into the 40s. North of Edinburg, and in sheltered pockets near the river, between 1 and 2 hours of hard freeze conditions - temperatures below 28 degrees - occurred around daybreak on the 4th. Through the period, temperatures held generally within a 3 degree range at any one location, between 28 and 32 degrees.
Fortunately, the long duration freeze was accompanied by a thickening coat of glaze ice.  This reduced the damage to citrus trees and fruit; agricultural extension agents noted minor damage to leaf, but tree damage was minimal. Unfortunately, the same stress caused more significant damage to tropical plants such as Emperor/Royal Palms and the sugar cane crop.  The Texas Agrilife Research Center in Weslaco reported some damage to cabbage, watermelon, peppers, leafy greens, and tomatoes. More significant damage was reported to the sugar cane crop, and goats (livestock) were lost at some ranches.  Damage estimates were preliminary of this writing.

Frost/Freeze in CAMERON, TEXAS
From 03-FEB-11 04:00:00 to 04-FEB-11 11:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 5.00M
Reported by: ASOS

Between 30 and 32 hours of freezing temperatures covered Cameron County, beginning during the early morning of February 3rd and continuing through late morning on February 4th, after which skies cleared and sunshine warmed temperatures back into the 40s.  Through the period, temperatures held generally within a 2 degree range at any one location, between 28 and 30 degrees.  Hard freezes - defined as 2 or more hours below 28 degrees - did not occur, but temperatures did touch 27 degrees in a few spots.
Fortunately, the long duration freeze was accompanied by a thickening coat of glaze ice.  This significantly reduced the damage to citrus trees and fruit.  Unfortunately, the same stress caused more significant damage to tropical plants such as Emperor/Royal Palms and the sugar cane crop.  All planted  Emperor Palms lost their fronds to the long duration freeze, as well as the glaze ice. The Texas Agrilife Research Center in Weslaco reported some damage to cabbage, watermelon, peppers, leafy greens, and tomatoes. More significant damage was reported to the sugar cane crop. Of 26,000 acres of sugar cane, 5500 were severely damaged.  Damage estimates were preliminary of this writing.

Frost/Freeze in WILLACY, TEXAS
From 03-FEB-11 04:00:00 to 04-FEB-11 11:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 1.00M
Reported by: ASOS

Between 30 and 32 hours of freezing temperatures covered Cameron County, beginning during the early morning of February 3rd and continuing through late morning on February 4th, after which skies cleared and sunshine warmed temperatures back into the 40s.  Through the period, temperatures held generally within a 2 degree range at any one location, between 28 and 30 degrees.  Hard freezes - defined as 2 or more hours below 28 degrees - did not occur on the 3rd, but there was likely 2 to 5 hours of temperatures below 28 degrees in a few pockets west and north of Raymondville on the 4th.
Fortunately, the long duration freeze was accompanied by a thickening coat of glaze ice.  This reduced the damage to citrus trees and fruit.  Unfortunately, the same stress caused more significant damage to tropical plants such as Emperor/Royal Palms and the sugar cane crop.  The Texas Agrilife Research Center in Weslaco reported some damage to cabbage, watermelon, peppers, leafy greens, and tomatoes. Sugar cane damage was minimal since much had been harvested and there is limited growth in the county.  Damage estimates were preliminary of this writing.