Guatemala's disaster relief spokesman says 73 people have been killed as a result of torrential rains brought by Agatha, which slammed into the region as a tropical storm before dissipating.
Salvadoran President Maruricio Funes says nine people are dead in his country, and Honduras has reported one fatality.
Agatha was dissipating Sunday over the mountains of western Guatemala a day after it made landfall near the nation's border with Mexico with winds up to 45 mph (75 kph).
Earlier AP reports saw the death toll in Central America rise to 44 from landslides and flooding triggered by first tropical storm of the year, as authorities struggled on Sunday to clear roads of debris and reach cut-off communities.
Torrential rains that pounded southern Mexico and Guatemala eased somewhat as rivers continued to rise and word filtered out from isolated areas of more deaths in landslides.
Guatemalan disaster relief spokesman David de Leon says there have been 13 deaths and 24 people were missing - a figure that only counted deaths it could directly confirm. Local Guatemalan authorities and rescuers reported 27 additional deaths in numerous landslides across the country. Four other deaths were reported in El Salvador and Honduras.
Agatha was dissipating over the mountains of western Guatemala, a day after it made landfall as a tropical storm near the nation's border with Mexico with winds up to 45 mph (75 kmh).
Although no longer even a tropical depression, Agatha still poses trouble for the region: Remnants of the storm were expected to deliver 10 to 20 inches (25 to 50 centimeters) of rain over southeastern Mexico, Guatemala and parts of El Salvador, creating the possibility of "life-threatening flash floods and mudslides," the U.S. National Hurricane Center in Miami said in an advisory.
As of Sunday afternoon, 75,000 people in Guatemala had been evacuated, many to shelters. At least 3,500 homes sustained major damage.
The mayor of San Antonio Palopo reported 13 deaths and seven people missing on Sunday after a landslide tore through the community on the steep banks of Lake Atitlan, a popular tourist attraction 65 kilometers (40 miles) east of Guatemala City. Andres Cumez told radio broadcaster Emisoras Unidas that the slide plowed through 30 homes.
Volunteer rescue crews reported at least 14 other deaths: Eight in two landslides in the Guatemala City area, and six in landslides in the northeastern towns of Quiche and Totonicapan.
On Saturday, Guatemalan President Alvaro Colom said 4.3 inches (10.8 centimeters) of rain had fallen in Guatemala City's valley in 12 hours.
The rains unleashed chaos in the department of Quetzaltenango, 125 miles (200 kilometers) west of Guatemala City, where a boulder loosened by rains crushed a house, killing four people including two children. Four children were killed when rain-soaked earth gave way in the town of Santa Catarina Pinula, about six miles (10 kilometers) outside the capital.
Cesar George of Guatemala's meteorological institute said the coastal community of Champerico had received 11.8 inches (30 centimeters) of rain in 30 hours.
Rainfall from the Guatemalan interior also flooded rivers coursing away from the storm toward the Atlantic. The Motagua River flooded 19 communities near Guatemala's northeastern border with Honduras.
In El Salvador, rains delivered by Agatha triggered at least 140 landslides throughout the country and killed two adults and a 10-year-old child. The exact cause of their deaths was unclear.
Civil defense officials said the Acelhuate River that passes through the capital, San Salvador, had risen to dangerous levels and was threatening to overflow into city streets.
Guatemala, El Salvador and Honduras have declared emergencies designed to increase immediate government aid and resources.
The Honduran national emergency agency Copeco reported one man was crushed to death by a wall that collapsed in the town of Santa Ana, near the capital of Tegucigalpa.
Flooding and slides destroyed 45 homes in the Honduras and prompted authorities to evacuate 1,800 people, according to figures released by the agency.
Also, a fishing boat was missing off the Pacific coast of Honduras with eight aboard, and a soldier went missing in eastern Honduras near the Nicaraguan border.
Agatha formed as a tropical storm early Saturday in the East Pacific.
