The death toll from floods in Visayas and Mindanao has risen to 25, officials said on 28 December, with storms expected to dump more rain over the hardest-hit southern and central regions.

Tens of thousands of people were forced to flee their homes as heavy rain submerged rural villages, towns and highways on Christmas Day, dampening festivities on the most important holiday in the mainly Catholic nation.

At least 13 people died, most from drowning, in the province of Misamis Occidental on the southern island of Mindanao, the national disaster agency said in updating the toll.

Twenty-six people were still missing. Nine have been injured.

The state weather forecaster said moderate to heavy rains were likely across southern and central regions on Wednesday and Thursday due to a low-pressure area off the coast that could develop into a tropical depression.

"Flooding and rain-induced landslides are likely, especially in areas that are highly or very highly susceptible to these hazards," the weather bureau said.

The disaster agency said relief efforts were under way to help people in areas hit hard by the flooding, as more than 81,000 people sheltered in evacuation centers.

Officials on Wednesday were to conduct aerial surveillance over Misamis Occidental to assess the extent of the damage.

The weather turned bad over the weekend as the disaster-prone nation of 110 million people prepared for a long Christmas holiday.

The Philippines is ranked among the most vulnerable nations to the impacts of climate change, and scientists have warned that storms are becoming more powerful as the world gets warmer.