Hurricane Harvey, the remnants of which continue to wreak havoc in Texas and made landfall in Louisiana on Wednesday, is expected to be the costliest natural disaster in US history, a veteran weather expert said Wednesday.

“This will be the worst natural disaster in American history. The economy’s impact, by the time its total destruction is completed, will approach $160 billion, which is similar to the combined effect of Hurricanes Katrina and Sandy,” said Joel Myers, president of forecasting company AccuWeather.

Myers said the staggering figure represents 0.08 percent of the gross national product, or GDP, which is $19 trillion.

“Business leaders and the Federal Reserve, major banks, insurance companies, etc. should begin to factor in the negative impact this catastrophe will have on business, corporate earnings and employment,” said Myers, who founded the weather service in 1962.

“The disaster is just beginning in certain areas. Parts of Houston, the United States’ fourth-largest city will be uninhabitable for weeks and possibly months due to water damage, mold, disease-ridden water and all that will follow this 1,000-year flood,” he said.

The worst flooding from the storm is yet to come as rivers and bayous continue rising in Texas — with additional levees at risk for breaches and failures, according to AccuWeather.

“The meteorologist forecasting community as a whole did a very good job in warning people about this storm,” Myers said.

But he said that “public officials were slow, in some cases, to react or to know what to do, which affected too many people and caused the loss of property and damage and destruction.

“This was unfortunate because when a natural disaster threatens, minutes and hours count and preparation and risk avoidance is imperative,” he added.

In Houston, Mayor Sylvester Turner was criticized for not ordering an evacuation before Tropical Storm Harvey struck the city.

He has defended his decision by arguing that an evacuation of Harris County would have resulted in a greater calamity for the residents.

“If you think the situation right now is bad, you give an order to evacuate, you are creating a nightmare. Especially when it’s not planned,” Turner said Sunday.