The first tropical storm of the season has left at least 18 people dead in Guatemala and El Salvador, officials in both countries said.
Tropical Storm Agatha was downgraded to a tropical depression on Sunday morning, but the damage caused by rains and high winds prompted the government in El Salvador to declare a state of emergency.
Civil defense chief Jorge Melendez said six people have been confirmed killed in weather-related accidents in El Salvador, and two others were missing.
In Guatemala, flash floods and mudslides killed 12 people and left 16 missing, the national disaster response agency said, adding that an estimated 20,000 people have been left homeless by the storm.
Colombia and the United States offered to send aircraft to ferry aid or help with evacuations of storm-hit areas.
Guatemala City's La Aurora International Airport, however, has been closed since Friday after being showered by volcanic ash from the eruption two days earlier of the Pacaya volcano. Two people were killed and three missing after the eruption on Wednesday.
US forecasters downgraded Agatha to a tropical depression on Saturday morning, saying it had weakened after crossing land.
At 0830 IST, the storm was located 45 kilometres east-northeast of Tapachula, Mexico, the Miami-based National Hurricane Center said.
Maximum sustained winds have decreased to 55 kilometres per hour, the center said, adding that all tropical storm warnings have been discontinued for the region.
"Additional weakening is anticipated as Agatha moves over the high terrain," the center noted.