Tropical Storm Debby has drenched northern Florida and killed several people as the downgraded hurricane churned towards Georgia and the Carolinas, threatening a week of torrential downpours and flooding across the region.

The slow-moving storm ploughed into Florida's Gulf Coast on Monday morning as a category 1 hurricane, crossing the coast near Steinhatchee about 115km southeast of Tallahassee, the National Hurricane Center said.

The storm carried hurricane-force winds of up to 130km/h when it struck in the Big Bend region - where the state's Panhandle meets its main north-south Peninsula - but speeds ebbed as Debby pushed over land.

Trees felled in the storm killed a 12-year-old girl and a 13-year-old boy in Levy County, officials and law enforcement said.

A 19-year-old man was killed near Valdosta, Georgia, when a tree fell onto a porch, police said.

Others killed in the storm included a truck driver who lost control of an 18-wheeler on Interstate 75 and went into the Tampa Bypass Canal, and a 38-year-old woman and her 12-year-old son whose SUV crashed in Dixie County north of Tampa in stormy weather, according to law enforcement.

The Indian state of Kerala was devastated in what government officials called one of its worst natural disasters. Most of the victims were tea estate workers.

Hundreds of rescue workers searched through mud and debris Wednesday from multiple landslides that have killed at least 151 people in southern India, police said.

The multiple landslides occurred after torrential rains triggered torrents of mud and water that swept through tea estates and villages.

Another 186 people were injured by the landslides that hit hilly areas in Kerala state's Wayanad district early Tuesday, flattening houses, uprooting trees and destroying bridges, said police officer Aijaz, who uses one name.

P.M Manoj, a spokesman for the state's top elected official, said that 187 people were unaccounted for. Seventy-seven bodies have been identified so far and mostly handed to their relatives, he added.

Landslides in Chooralmala and Mundakkai have plunged Kerala into mourning, with the death toll now exceeding 330.

Officials worry the number could climb higher, as more than 220 people remain missing.

Due to relentless rainfall, rescue operations that were supposed to continue until 4 pm were cut short on Thursday.

The Mundakkai landslide in Kerala's Wayanad has resulted in 387 deaths, with 172 bodies identified and 8 cremated on Sunday (Aug 04).

Search efforts continue for 180 missing individuals, with authorities limiting access to Chooralmala to facilitate the search.

Meanwhile, schools in Wayanad, except those used as relief centers, will reopen today after a series of holidays.

The death toll from the Wayanad landslides has crossed 400 as of Wednesday, with more than 150 still missing.

Rescue operations are underway, with teams now focused on the forested regions.

The Kerala government has also enlisted the help of the families of the missing and local residents in the search efforts.