Little to no rain fell across the Rio Grande Valley and Deep South Texas during the first ten days of May. Widespread rains from late on the 10th through early on the 12th, with scattered rains through the 13th, would improve conditions by the May 14th Drought Monitor update.
The general lack of rainfall allowed for no improvement in drought conditions until then. However, the rainfall in late April prevented drought conditions from deteriorating across the region. Extreme (D3) to Exceptional (D4) drought conditions continued to blanket the area.  Some areas, particularly extreme southeastern Starr through western Hidalgo County, and much of the Kenedy County King Ranch area, missed the significant rainfall and remained in Exceptional Drought through the entire month.

Drought in KENEDY, TEXAS
From 01-MAY-13 00:00:00 to 31-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

Little to no rain during the first week of May allowed for all of Kenedy County to remain entrenched in Exceptional (D4) Drought conditions.  Patchy rainfall between the 10th and 13th near the coast helped trim a sliver of the D4 area to D3 (Extreme Drought) by May 14th.  Locally heavy rains estimated at 1 to 2 inches west of Highway 77 would further trim this area back from D4 to D3; however, the majority of the county held at D4 through the month.

Drought in STARR, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

Little to no rain during the first week of May allowed for all of Starr County to remain entrenched in Exceptional (D4) Drought conditions.

Drought in WILLACY, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

Little to no rain during the first ten days of May allowed for the vast majority of Willacy County to be encompassed by Exceptional (D4) drought conditions, except for an area of Extreme (D3) Drought conditions in the south central portion of the county. Conditions would improve after locally heavy rainfall on the 11th, in time for the May 14th Drought Monitor update.

Drought in ZAPATA, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

For the first ten days of May little to no rain fell, resulting in the northern two thirds of Zapata County experiencing Extreme (D3) Drought conditions, except for the southern third, which was affected by Exceptional (D4) Drought conditions.  Locally heavy rain from strong thunderstorms late on the 10th, and again periodically through the 13th, would improve conditions rather dramatically by mid month.

Drought in BROOKS, TEXAS
From 01-MAY-13 00:00:00 to 27-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

The lack of rainfall resulted in most of Brooks County being entrenched in Exceptional (D4) Drought conditions the first week of May, except for an area of Extreme (D3) Drought conditions over the western central portion of the county. Periods of rain and scattered thunderstorms between May 10 and 15 would scour out the D4 area to just the eastern third of the county.  Torrential rains on May 24th would help improve conditions by the last few days of the month.

Drought in CAMERON, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

Little rainfall resulted in the great majority of Cameron County experiencing Extreme (D3) Drought conditions during the first week of May. Exceptional (D4) Drought conditions held firm across the NW and the NE corners of the county.

Drought in COASTAL CAMERON, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

Little rainfall resulted in the northern half of coastal Cameron County continuing in Exceptional (D4) Drought conditions, while the southern half held onto Extreme (D3) Drought conditions.

Drought in COASTAL WILLACY, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

The general lack of rainfall during the first week of May allowed for all of coastal Willacy County was mired in Exceptional (D4) Drought conditions.

Drought in HIDALGO, TEXAS
From 01-MAY-13 00:00:00 to 31-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

A general lack of rainfall allowed for all of Hidalgo County to be mired in Exceptional (D4) drought conditions the first week of May, except for the SE corner which experienced Extreme (D3) drought conditions.  Locally heavy rains, generally between 1 and 3 inches from Mercedes to Weslaco between the 10th and 15th reduced the area of D4 to the western and northern portion of the county through May 21st.  Bands of heavy rain across the north third of the county on May 24th improved these areas from D4 to D3 by the 28th.  However, D4 remained across the western and central portions of the county - who missed the periodic heavy rainfall.

Drought in JIM HOGG, TEXAS
From 01-MAY-13 00:00:00 to 13-MAY-13 23:59:00 (CST-6)
Property damage: 0.00K
Reported by: Drought Monitor

A lack of rainfall allowed for most of Jim Hogg County to continue in Extreme (D3) Drought conditions, except for a sliver of Exceptional (D4) Drought conditions along the southern county border.