A for sale sign in front of a home in Arlington, Va., on Aug. 22, 2023. (Andrew Caballero-Reynolds/AFP via Getty Images)

Affordable home listings reached a 19-month high in September due to "short-lived mortgage rate relief," a new Zillow analysis shows.

According to the report released on Monday, a middle-income household would have been able to afford more homes on the market in September than in any month in more than a year and a half.

Mortgage rates in the month of May averaged 7.06 percent, the data shows. A household making the median U.S. income could have comfortably afforded 22.7 percent of homes listed for sale across the country.

Then in September, mortgage rates fell to an average of 6.18 percent. That month, about 75,000 additional homes on the market were affordable to a median-income household.

In the weeks since then, however, mortgage rates have risen to 6.78 percent as of Nov. 14. The sharp reversal likely caused some prospective buyers to retreat from the home-buying process, according to Zillow.

The unpredictable mortgage rate landscape may limit choices for home buyers and may also prevent them from entering the housing market altogether.

"Affordability remains the top challenge for first-time home buyers especially, and buying power can change quickly with the unpredictable nature of mortgage rates," Orphe Divounguy, a senior economist for Zillow Home Loans, wrote in a statement.

"Buyers should expect more ups and downs ahead for mortgage rates. While there's no guarantee, signs point to rates moving a bit lower into next year. However, the path will be bumpy, and buyers should stay ready to move forward when the time is right for them," Divounguy said.

Overall affordability continues to be an issue for potential homebuyers after rates have leveled off following a six-week climb, according to FreddieMac.

As financial markets adjusted to President-elect Donald Trump's second term in office, mortgage rates essentially stayed flat this week.

According to Freddie Mac data, the average 30-year mortgage rate was unchanged at 6.78 percent for the week through Wednesday, compared to 6.79 percent a week earlier.

On the campaign trail, Trump vowed to make homeownership more affordable by lowering mortgage rates through policies aimed at knocking out inflation.

Some economists say Trump's election victory, however, has clouded the outlook for mortgage rates.

The president-elect's proposals could set the stage for higher mortgage rates, according to Danielle Hale, chief economist at Realtor.com.

"Given what we're seeing in bond markets, investors are expecting higher rates under a Trump administration and are starting to position in that direction already," Hale said in a statement. "So, if overall rates are higher, that would tend to also mean that mortgage rates would move higher, too."

Lisa Sturtevant, chief economist with Bright MLS, also believes that the mortgage rate landscape is uncertain going into Trump's second term.

"Trump's fiscal policies can be expected to lead to rising and more unpredictable mortgage rates through the end of this year and into 2025," Sturtevant said in a statement.

On the other hand, Zillow expects rates to move lower into next year, but that could change as new economic data is released.