Surface high pressure with a touch of arctic air spread across all of Texas during the first full week of December, reaching the Rio Grande Valley on the 7th and continuing into the morning of the 8th, bringing several hours of temperatures at or below freezing.

Frost/Freeze in HIDALGO, TEXAS
From 08-DEC-11 00:00:00 to 08-DEC-11 07:45:00 (CST-6)
Reported by: COOP Observer

Temperatures fell to 32 degrees around midnight and continued falling into the 20s and lower 30s mainly east of the highly populated stretch of Hidalgo County along the Highway 281 corridor, as well as east to west along State Highway 186/Farm to Market 1017 from near San Manuel to Puerto Rico. Temperatures rose above 32 degrees around 745 AM. Minimum temperature dropped to 26 degrees at the Cooperative Observer site in San Manuel and at the Santa Ana RAWS site. A citizen weather site in Edinburg also recorded a minimum of 31.4 degrees.

Frost/Freeze in BROOKS, TEXAS
From 08-DEC-11 02:00:00 to 08-DEC-11 07:30:00 (CST-6)
Reported by: ASOS

The automated surface observing system at Brooks County Airport, 3.5 miles southeast of Falfurrias, reported several hours of temperatures at 32F, interrupted by short periods just above freezing.  Interpolation between the more sheltered observation at the Lower Rio Grande NWR east of San Manuel (Hidalgo County) suggests that temperatures in rural ranchlands fell as low as 30F or more through the night.

Frost/Freeze in KENEDY, TEXAS
From 08-DEC-11 02:00:00 to 08-DEC-11 07:30:00 (CST-6)
Reported by: ASOS

The cooperative observing locations at Sarita and Armstrong reported low temperatures of 29F a between 7 and 8 AM on December 8th.  Based on proxy observations from the Brooks County Airport (several hours beginning at 215 AM and ending just before 7 AM), the Lower Rio Grande Valley NWR site at San Manuel (around 5 miles southwest of the Kenedy/Willacy/Hidalgo border), and Kingsville NAS (4 hours below freezing, low temperature 27F), Kenedy County had at least five hours of freezing temperatures early on the 8th.

Frost/Freeze in JIM HOGG, TEXAS
From 08-DEC-11 02:00:00 to 08-DEC-11 07:45:00 (CST-6)
Reported by: ASOS

The Jim Hogg County Airport, 5 miles northwest of Hebbronville, recorded a little more than 2 hours of freezing temperatures, with a low of 30F just before 6 AM CST on the 8th.   Based on interpolated observations in Brooks and Zapata County, at least five hours of freezing temperatures likely occurred from Hebbronville through the open ranchlands of Jim Hogg County during the early morning hours.

Frost/Freeze in ZAPATA, TEXAS
From 08-DEC-11 03:15:00 to 08-DEC-11 08:00:00 (CST-6)
Reported by: ASOS

Temperatures fell to 32 degrees between 315 and 8 AM, and continued falling into the 20s to around 30 across Zapata County before rising above 32 degrees after 8 AM. Minimum temperatures dropped to 26 .6 degrees at the Zapata County Airport.

Frost/Freeze in STARR, TEXAS
From 08-DEC-11 03:15:00 to 08-DEC-11 07:45:00 (CST-6)
Reported by: ASOS

Temperatures fell to 32 degrees (32F) between 315 and approximately 745 AM, and continued falling to 30F or perhaps a little lower across Starr County (by interpolation of observations in Zapata and Jim Hogg County) before rising above 32F after 8 AM. Minimum temperatures dropped to 30F at Falcon Lake Remote Automated Weather System site; 26 degrees at Falcon Dam Cooperative, and 31F at Rio Grande City.  La Joya, about 6 miles east of the county line in Hidalgo, recorded a low of 34F.