Buckle in for a brutal free-fall in home prices and US housing is in a massive b...

• The US housing market is cratering, as the Fed's rapid interest rate hikes send mortgage costs soaring.

• Home sales have fallen for 8 months, and prices are dropping. But economists say worse is to come.

• Here's what Jeremy Siegel, Paul Krugman and 5 other top experts say about how painful things will get.

The alarm bell is already ringing for American homeowners, as surging mortgage rates scare away buyers — and the slump in the US housing market is only going to get worse, experts say.

The signs of stress have become blatant. Recent data showed that in September, existing home sales dropped 24% — the eighth straight monthly decline, marking the longest slide since 2007. Homebuilding starts slumped, and the number of new home listings fell 22%.

Behind the deteriorating housing market is the Federal Reserve, which is aggressively raising interest rates to fight 40-year high inflation. That has sent mortgage rates soaring to 20-year highs.

That has made buying a home more expensive, prompting buyers to back off — mortgage applications are at their lowest since 1997. Meanwhile, growing concerns about a coming economic recession have dampened demand.

Here's what 7 top experts are warning about what happens next.

Jeremy Siegel, Wharton professor of finance

"I expect housing prices fall 10% to 15%, and the housing prices are accelerating on the downside," Siegel told CNBC in a recent interview, noting that housing prices by any indicator are going down.

In a separate interview with CNBC, he said: "I think we're gonna have the second-biggest housing price decline since post WWII period over the next 12 months. That's a very, very significant factor for wealth [and] for equity in the housing market."

Mark Zandi, chief economist at Moody's Analytics

"Buckle in. Assuming rates remain near their current 6.5% and the economy skirts recession, then national house prices will fall almost 10% peak-to-trough," he said in a recent tweet. "Most of those declines will happen sooner rather than later. And house prices will fall 20% if there is a typical recession."