“I confirm that Batsirai hit Mananjary at about 8pm (17:00 GMT) local time,” meteorologist Lovandrainy Ratovoharisoa told AFP news agency, but gave no further details.
Residents hunkered down before the storm’s arrival and winds of more than 200km per hour (124 miles per hour) were forecast as it bore down on the country still recovering from the deadly Tropical Storm Ana in late January.
The eye of the storm was forecast to cross the centre of the island overnight into Sunday, before leaving its western shores by Monday.
Winds could reach “more than 200 or even 250 km/h … at the point of impact” and waves could reach as high as 15 metres (50 feet), Meteo-France said.
The United Nations said it was ramping up its preparedness with aid agencies, placing rescue aircraft on standby and stockpiling humanitarian supplies.
The impact of Batsirai on Madagascar is expected to be “considerable”, Jens Laerke, spokesman for the UN’s humanitarian organisation OCHA, told reporters in Geneva on Friday.
At least 131,000 people were affected by Ana across Madagascar in late January. At least 58 people were killed, mostly in the capital Antananarivo. The storm also hit Malawi, Mozambique and Zimbabwe, causing dozens of deaths.
The UN’s World Food Programme (WFP) pointed to estimates from national authorities that some 595,000 people could risk being directly affected by Batsirai, and 150,000 more might be displaced due to new landslides and flooding.
“We are very nervous,” Pasqualina Di Sirio, who heads the WFP in Madagascar, told reporters by video link from the Indian Ocean island.
Search and rescue teams on the island have been placed on alert and residents reinforced their homes.
Sitting on top of his house, Tsarafidy Ben Ali, a 23-year-old coal seller, held down corrugated iron sheets on the roof with large bags filled with soil.
“The gusts of wind are going to be very strong. That’s why we’re reinforcing the roofs,” he told the AFP news agency.
The storm poses a risk to at least 4.4 million people in one way or another, the International Federation of Red Cross and Red Crescent Societies said.