The previous toll in Guatemala was 176 on Friday, when rescuers discovered 36 bodies in Solola Department west of the capital, President Oscar Berger said, noting that hundreds were still missing.
The storm has also killed 67 people in El Salvador, 24 in Mexico and 11 in Nicaragua, the authorities in those countries said.
Tens of thousands were left homeless across the region.
Stan slammed ashore as a hurricane in the Mexican state of Veracruz early on Tuesday but began pounding northern Central America with rain on 1 October, with Guatemala taking the hardest blow.
Berger had warned Guatemalans on Friday to prepare for greater losses.
"We are going to have unpleasant surprises. There are many missing, many landslides, towns cut off," he said.
Most of those killed in Guatemala were indigenous people who lived along the banks of Lake Atitlan, in the west of the country.
The area was buried in massive mudslides, as tons of mud poured down the sides of the mountains surrounding the lake.