The supply of homes for sale increased very slightly nationally in June, according to the National Association of Realtors, but in Redfin's major market index, the total number of homes for sale was 3.8 percent lower than a year ago and there were 1.6 percent fewer new listings.

As a result, the number of people requesting home tours fell 6.1 percent annually in June, according to Redfin's index, which is seasonally adjusted and covers 15 large metropolitan housing markets. There were 15 percent fewer offers made on homes as well.

Red-hot home prices, rising mortgage interest rates, very few listings at the entry level and a high rate of student loan debt have weighed on buyers for a while, but a strong economy and growing employment had mitigated those factors. Now, however, a market stalemate is developing as rates and prices continue to rise, further weakening affordability.

The long list of housing headwinds is finally taking its toll on potential buyers. Housing demand fell 9.6 percent in June, compared with June 2017, according to a monthly index from Redfin. That is the largest decline since April 2016.

While supply declined overall, Redfin noted a large rise in listings in some of the most supply starved markets, which is where home prices have overheated most. Those include Seattle and Washington, D.C., which both saw double-digit increases in the number of homes for sale in June. Demand in both of those markets, however, fell.

"As much-needed large inventory increases finally arrive in some of the hottest markets, buyers are taking the opportunity to be choosy, offering only on well-priced homes," said Pete Ziemkiewicz, head of analytics at Redfin. "Buyers in Seattle are even keeping offer contingencies like the inspection intact, something that has been increasingly rare in recent years. With more homes to go around, buyers don't need to bid as aggressively to win bidding wars, so prices, while still growing, are growing a lower rate, and home sales are slowing."

Some real estate agents in Southern California, where home sales plummeted in June, according to CoreLogic, also reported a drop in the number of bidding wars.

"We're still selling most every home, but now it's usually with just one or two offers over the 10 to 15 offers we were seeing earlier in the year," said David Fogg, an agent at Keller Williams Realty.

In other markets, where home prices have not overheated as much, demand is still rising. Chicago and Atlanta both saw demand gains on the Redfin index, despite sizable drops in the supply of homes for sale. As a comparison, home prices in Seattle were up more than 13 percent in May, according to the latest S&P/Case-Shiller home price report, while prices in Atlanta were just 5 percent higher and in Chicago just 3 percent higher.