The storm caused damage worth around 40 million US dollars.
Sixty-eight people were killed and 130,000 displaced when the tropical storm Chedza hit Madagascar on Jan. 16, the National Bureau of Risk Management and Disaster said.
The storm also lashed Malawi, Mozambique and Zimbabwe in one of the worst disasters to hit the region in years. Rivers burst their banks, flooding vast areas and destroying homes, bridges and crops.
(READ MORE: Malawi says to miss 2015 economic growth forecast after deadly floods)
"The country is in a state of disaster and officially appeals for aid both nationally and internationally," Prime Minister Jean Ravelonarivo said on national radio on Wednesday.
Ravelonarivo estimated the damage at more than 100 billion ariary, roughly 40 million US dollars, and said major flooding had "caused massive degradation of key infrastructure".
Madagascar is one of the world's poorest nations and is currently also battling a plague epidemic which has killed at least 57 people since August.
The island's economy was battered after a 2009 coup that drove away donors and investors. A peaceful 2013 election has brought back some aid, but the nation is still struggling to impose stable government and economic reforms.
(READ MORE: Madagascar showing recovery signs: IMF)
The IMF said Madagascar's economy early signs of recovery in 2014 with growth estimated at 3 percent, which could rise to 5 percent in 2015, but political instability, weak institutions and weak governance are hurting prospects.