The worst-affected state was Puebla in central Mexico, where at least 28 people were killed after torrential rains set off mudslides.
Puebla Governor Rafael Moreno Valle said dogs had been brought in to search for those missing.
Officials said some outlying areas had not yet been reached.
At least 40 people have been confirmed dead after Tropical Storm Earl moved over Mexico on Saturday.
Earl had earlier hit Belize and Guatemala in Central America.
But it was in the Mexican states of Puebla, Veracruz and Hidalgo where its heavy rains caused most damage.
Among those killed in Puebla were 15 children who died when their homes were buried by mud which slid down the rain-soaked hills.
A whole hill collapsed near Huauchinango, sweeping down on a nearby village.
"It is a tragedy what has happened to our people in Huauchinango," Mayor Gabriel Alvarado said.
About two hundred people were left homeless in the state of Puebla alone.
In neighbouring Veracruz, 11 people were killed and in Hidalgo a 15-year-old died in hospital after being pulled from the mud.
More than 10,000 people were affected and 18 villages remained cut off in the eastern state.
The US National Hurricane Center (NHC) has warned of another storm approaching Mexico.
It said Tropical Storm Javier could strengthen into a hurricane by Monday afternoon local time.
"On the forecast track, the centre of the tropical cyclone should pass near or over the southwest coast of Mexico later today, and approach the southern portion of Baja California peninsula on Monday," the NHC said.

Louise Wright, from Mapperley, died after she was hit by a lorry in Nottingham city centre earlier this month.
A bike which has been painted white, known as a ghost bike, has been left at the scene along with floral tributes.
Her partner James Faulkner said he hoped it would promote cycle safety.
Ms Wright, who worked for fashion firm Paul Smith, died on 3 July after the crash involving an HGV in Lower Parliament Street.
The ghost bike, thought to be the first in the East Midlands, appeared recently along with tributes to the popular 29-year-old.
Mr Faulkner said he and Ms Wright's family had taken comfort from many well-wishers' kind words.
"We still don't know the circumstances of the accident yet, but I hope that the ghost bike will help raise awareness of cyclists on the roads," he said.
"If it can help prevent any future accidents, then it will have served a purpose and could help save a life."
Tributes were also paid to Ms Wright on Facebook, including by the Nottingham Roller Girls roller derby team who described her as beautiful, vibrant and funny.
Mike Hallam, duty manager at business Machine Mart next to the crash scene, said some people had reservations about the memorial.
"I dare say most people were touched but there were a few mixed reactions, whether it was tasteless or not," he said.
"Personally I think it was a very good idea."
Leaving a white bike at the scene of a fatal crash started in the United States but has been a growing phenomena across the UK over the last few years.
Emergency workers in Mexico are searching for survivors after landslides killed dozens in the wake of Tropical Storm Earl.
[NEXT_CONCEPT]
The partner of a cyclist who died in a crash involving a lorry said he hopes a "ghost bike" memorial to her will help prevent more deaths.