According to local officials, at least 30 people have died, and hundreds have been forced to vacate their homes as storms and torrential rainfall continue to pound Central America.
Salvadoran authorities said on Friday that the death toll had risen to 19, including six children, while more than 3,000 people remain in temporary shelters.
"We must save people's lives," Luis Amaya, who heads El Salvador's civil protection agency, told reporters Friday.
"Material goods come and go, but now we must focus on protecting lives."
On Friday, Guatemalan officials reported 10 deaths, over 11,000 people evacuated, about 380 remaining in temporary shelters, 300 seriously damaged properties, and four bridges demolished.
They said the rains had blocked off 180 villages and damaged 22 homes.
In Mexico, experts predict heavy rainfall throughout most of the nation, as well as torrential downpours along the Pacific and Atlantic coastlines and farther inland, bringing lightning, high gusts, potential hail, and river floods.
The rains forced officials to evacuate 80 patients from a children's hospital in Oaxaca state on Thursday. Still, they also provided much-needed relief to drought-stricken reservoirs across the country, now at around a third of capacity.
The Conagua water authority in Mexico warned of wind speeds of up to 70 kilometers per hour (44 mph) and waves of up to 3 meters along the Gulf and Caribbean beaches.
According to the National Hurricane Centre, the rains were caused by low-pressure channels interacting across much of the country and a monsoon trough drawing moist ocean air from far into the North Pacific. The remnants of Alberto, the Atlantic hurricane season's first named tropical storm, also contributed to the rains.
Alberto killed at least four people when it moved across northeastern Mexico this week.
The National Hurricane Centre in the United States forecast heavy rains will continue through Friday across southern Mexico and northern Central America, with thunderstorms and showers as far south as Costa Rica and Panama throughout the weekend.
