The tropical storm made landfall on the Yucatán Peninsula near Cancún early on July 21, leaving at least 17 people dead in Guatemala.

[3] The storm caused 212,000 customers to lose power in Texas as well as 125,000 in Tamaulipas, and dropped estimated amounts of over 16 inches (410 mm) of rain in isolated areas.

Despite producing strong convection and tropical storm-force sustained winds, it failed to develop a low-level circulation until July 20.

That morning, reconnaissance aircraft found a low-level circulation and the system was identified as a tropical cyclone by the National Hurricane Center (NHC).

[8] Originally, the storm was forecast by the Servicio Meteorológico Nacional (Mexico's national weather service) to make landfall between Playa del Carmen and Tulum.

[11] In essence, this caused the storm to briefly move parallel to the coastline, shifting the point of Dolly's first landfall to north of Cancún.

[12] After moving into the Gulf of Mexico, conditions became favorable for additional intensification, with low wind shear and warm sea surface temperatures.

[3] At 1:00 pm CDT (1800 UTC) that same day, Dolly made landfall on South Padre Island, Texas, slightly weaker as a Category 1 hurricane with 85 mph (137 km/h) sustained winds and a pressure of 967 mbar.

South Padre Island, Port Isabel, Laguna Vista, Los Fresnos, Bayview, Brownsville, San Benito, Rio Hondo, Arroyo City and especially Harlingen suffered heavy wind and flooding.

Towns like Santa Rosa, La Villa, Edcouch, Elsa, Monte Alto and San Carlos were hit hard by the slow-moving, wet hurricane which dumped 10-20 inch rains.

The remnant low of Dolly finally began to dissipate late in the evening of July 27 approximately 100 km (62 mi) west-northwest of Dalhart, Texas.

[16] On July 20, the Mexican government issued a tropical storm warning for the Yucatán Peninsula from Campeche to the international border with Belize.

[17] That same morning, the Quintana Roo Civil Protection authorities in Chetumal declared a "blue alert" for the entire state due to the storm's proximity.

Diamond Offshore Drilling removed non-essential employees from some of its rigs,[26] and Rowan Companies also evacuated one of its eight oil platforms in the Gulf.

[33] Cameron County emergency officials urged residents living along the Rio Grande to evacuate, for fear of the levees alongside the river bursting.

[35] The United States Navy removed 104 airplanes from Truax Field and flew them to bases further inland, and Immigration and Customs Enforcement evacuated its detention facility in Port Isabel.

[37] In Tamaulipas, state authorities put the municipalities of Soto la Marina, San Fernando, Matamoros, Valle Hermoso, Río Bravo and Reynosa on alert and prepared shelters.

[38] On July 23, Coahuila authorities emitted an orange alert due to the risk of flooding from Dolly's remnants, and activated 2,000 military and police to the state.

No deaths were reported as a result of the storm, but one boy was injured after falling seven floors from a condominium balcony in South Padre Island.

[60] Near noon on July 24, an EF0 tornado touched down in the southern edge of downtown San Antonio near the Interstate 10–Interstate 37 interchange.

[61] Flash flooding from the remnant low of Dolly occurred in El Paso, Texas, on July 26:[62] one person was killed in an adjacent portion of New Mexico from a weather-related traffic accident.

[74] On July 26, the remnant low of Dolly dropped heavy rains on Ciudad Juarez, Chihuahua, causing landslides, flooding, the collapse of a historic church[75] and evacuation of numerous colonias.