The storm produced widespread moderate to heavy rain in Mexico, with accumulations peaking at 15.23 in (387 mm) in La Encantada, Tamaulipas.

[1] Formation of a banding feature along the southeastern portion of the circulation on September 1 marked the system's transition into a tropical depression by 18:00 UTC while over the Bay of Campeche.

[1][3] It was uncertain if a closed circulation truly existed due to conflicting data and the depression could have remained a trough until the afternoon of September 2.

[1] Early on September 2, the depression acquired gale-force winds and became the fourth tropical storm of the 2014 season; accordingly, it was assigned the name Dolly at this time.

[1] A tight pressure gradient between Dolly and a ridge over the Gulf of Mexico created a large area of tropical storm winds along the east side of the cyclone.

[4] Data Hurricane Hunters investigating the system indicate that Dolly achieved its peak winds of 50 mph (80 km/h) around 12:00 UTC.

Winds up to 70 mph (110 km/h) were found within the deep convection to the storm's east but considered to be inflated by heavy rains and thus not representative of its actual strength.

Around 01:00 UTC on September 3, Dolly's pressure fell to 1000 mbar (hPa; 29.53 inHg) marking the storm's peak intensity.

Maintaining a due west course, Dolly made landfall just south of Tampico at 04:00 UTC with winds of 45 mph (72 km/h).

[8] Dozens of Mexican fishing vessels sought refuge in the Port of Brownsville; however, two ran aground in the shipping channel and a third on South Padre Island.

[9] Southerly flow from Hurricane Norbert over the Pacific brought moisture from Dolly over the Southwestern United States, resulting in possible life-threatening flash flooding.