A cool and dry airmass was in place over Deep South Texas owing to a strong surface high. Another round of efficient radiational cooling led to temperatures falling below freezing across much of the area, excluding the immediate coast and the lower Valley (Cameron County).

Frost/Freeze in BROOKS, TEXAS
From 12-JAN-21 22:45:00 to 13-JAN-21 09:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Temperatures fell below freezing around 10:45 PM on January 12th and remained below freezing until 9:00 AM on the 13th. Low temperatures fell into the middle and upper 20s across the area. A minimum temperature of 26 degrees was observed at the Calosa 1 Mesonet. Brooks County Airport observed a low of 27 degrees, while the La Rucia Mesonet recorded a low of 29 degrees.

Frost/Freeze in STARR, TEXAS
From 13-JAN-21 01:00:00 to 13-JAN-21 09:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

Temperatures fell below freezing around 1:00 AM on January 13th and remained below freezing until 9:00 AM. Low temperatures fell into the upper 20s across the area. A minimum temperature of 28 degrees was observed at the Falcon Lake RAWS site. The Rancho Los Comitas COOP site also recorded a low of 28 degrees.

Frost/Freeze in INLAND KENEDY COUNTY, TEXAS
From 13-JAN-21 01:30:00 to 13-JAN-21 09:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Temperatures fell below freezing around 1:30 AM and remained below freezing until 9:00 AM. Low temperatures fell into the upper 20s and lower 30s across the area. A minimum temperature of 29 degrees was observed at the Sarita Union Pacific Railroad (UPR) mesonet site. The ARMSTR UPR site also observed a low temperature of 32 degrees.

Frost/Freeze in NORTHERN HIDALGO COUNTY, TEXAS
From 13-JAN-21 01:45:00 to 13-JAN-21 08:45:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

Temperatures fell below freezing around 1:45 AM and remained below freezing until 8:45 AM. Low temperatures fell into the upper 20s and lower 30s across the area. A minimum temperature of 28 degrees was observed at the Linn-San Manuel RAWS site.

Frost/Freeze in JIM HOGG, TEXAS
From 13-JAN-21 03:00:00 to 13-JAN-21 08:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Temperatures fell below freezing around 3:00 AM and remained below freezing until 8:30 AM. The Hebbronville airport recorded a low temperature of 31 degrees. Given low temperatures in the upper 20s observed in adjacent Brooks and Starr Counties, it is implied that temperatures across central and southern Jim Hogg were likely colder than what was observed in Hebbronville.

Frost/Freeze in ZAPATA, TEXAS
From 13-JAN-21 04:15:00 to 13-JAN-21 08:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Temperatures fell below freezing around 4:15 AM and remained below freezing until 8:30 AM. Low temperatures fell into the lower 30s across the area. A minimum temperature of 30 degrees was observed at the Zapata airport.

Frost/Freeze in SOUTHERN HIDALGO COUNTY, TEXAS
From 13-JAN-21 04:15:00 to 13-JAN-21 08:15:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Temperatures fell below freezing around 4:15 AM and remained below freezing until 8:15  AM. Low temperatures fell into the lower 30s across northern portions of Southern Hidalgo. A minimum temperature of 32 degrees was observed at Edinburg International Airport.

Frost/Freeze in WILLACY, TEXAS
From 13-JAN-21 06:00:00 to 13-JAN-21 08:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Temperatures fell below freezing around 6:00 AM and remained below freezing until 8:00 AM. Low temperatures fell into the lower 30s across the area. A minimum temperature of 30 degrees was observed at the YTURIA Union Pacific Railroad mesonet site.