It was the best of times…but really it was the worst of times. The combination of 7%-plus mortgage rates and rising home prices makes October the least affordable month for buying a house this century.

Mortgage rates, which hit a near 23-year high last month at 7.31% (today they’re 7.57%, according to Freddie Mac), strained buyers and sellers alike. Sellers are reluctant to let go of the homes they bought at sub-3% mortgage rates, while some buyers face spending upwards of 60% of their income on housing.

The dichotomy of both sellers’ unwillingness to sell and buyer apprehension has caused what real estate experts and economists refer to as the “lock-in” effect, which is leading to low existing-home sales volumes.

“It’s a tale of two markets,” Priscilla Almodovar, Fannie Mae CEO, told MarketWatch in an interview at the Mortgage Bankers’ Association’s annual conference. “Homeowners are in good shape because they probably have a lot of equity in their homes.

Plus, “they probably have a mortgage that’s 2%, 3%, 4%,” she added, but they are constrained by a “lock-in effect of not giving up that mortgage.”

At this point, many real estate experts and economists are unsure of when the housing market could be recalled to life. With the Federal Reserve’s commitment to “higher for longer” interest rates, mortgages eclipsed 7.5% last week.

“It is likely [that mortgage rates] will stay around that level or even get closer to 8% in the last few months of the year, especially if the Fed does raise rates one more time before the year is done,” Mark Fleming, chief economist at Fortune 500 financial services company First American, tells Fortune.

If mortgage rates remain high, both buyers and sellers will feel the pain until well into 2024. For now, prospective homebuyers’ buying power—how much one can buy based on changes in income and mortgage rates—is down more than 6% during the past two months, Andy Walden, vice president of enterprise research for ICE Mortgage Technology, tells Fortune.

“This could slow transaction speeds and may ultimately weigh on what had been a historically strong level of home price growth throughout the spring and summer,” he says.

The average existing home sale exceeds $310,000, according to the Case-Shiller U.S. National Home Price Index, nearly double the cost just a decade ago. Year to date, home prices are up more than 5%.

Home prices rising in tandem with mortgage rates are making today’s housing market the last affordable it’s been since the early 2000s. In fact, the housing market has gotten so expensive that U.S. incomes would have to surge 55% for homebuying to be considered affordable, Walden said in a recent CNBC interview.

“If you look at home affordability itself and what it would take to normalize the market today,” he told Kelly Evans of CNBC’s The Exchange, “it’s a 35% correction in price, or a 4% decline in [mortgage] rates, or a 55% growth in income—some combination of those.”

And as homebuying becomes further out of reach for many, the number of existing home sales has fallen. National Association of Realtors data confirms that 2023 is shaping up to be the lowest year in terms of number of home sales since the housing bubble burst in 2008. At its current pace, total existing-home sales in 2023 are projected to total 4.1 million, according to NAR, far short of the more than 6 million sold in 2021.

“The combination of reduced affordability and an even stronger rate lock-in effect suppresses [the number of] home sales,” Odeta Kushi, deputy chief economist at Fortune 500 financial services company First American, previously told Fortune. “You can’t buy what’s not for sale, even if you can afford it.”