Southern California’s housing market enters the typically slower-selling fall season relatively awash in listings amid a significant cooling of house hunters’ willingness to make a deal.

“New cracks in the housing market are demonstrating that the cooling trend is here to stay,” wrote Steven Thomas of ReportsOnHousing that tracks homebuying patterns found in real estate broker networks.

Thomas’ biweekly report found a stark change in the market for existing homes as of Sept. 20 vs. a year ago: selling time was 26 days longer as listings grew by 22 percent. ReportsOnHousing watches supply (active listings); year-to-date increase in supply; demand (new escrows in past 30 days); and “market time” (a measure of selling speed, estimated days it takes a typical listing to enter escrow).

As summer ended, the four-county region covered by the Southern California News Group had 36,923 listings, up 6,548 in a year or 22 percent. It’s also up 10 percent vs. the six-year average. Note that Southern California builders’ unsold inventory, which is not included in this study, stood at 3,336 in the second quarter, the highest in six years, according to MetroStudy.

Sellers have rushed to market as year-to-date supply has grown sharply: Up 13,774 listings vs. a rise of 2,787 in the same period in 2017 — yes, a nearly five-fold increase.

Surprisingly, in a market that was once seen as supply-starved, house hunters have pulled back despite the significant increase in choices.

On Sept. 20 there were 11,603 new escrows, down 1,473 sales contracts in 12 months, or an 11 percent drop. Don’t blame the local job market for the reluctance to buy: Southern California payrolls are up 1.7 percent in the year ended in August, just a bit slower than 1.9 percent a year ago and 2.6 percent two years ago.

More supply and fewer purchases mean ReportOnHousing’s “market time” metric for selling speed rose to 95 days vs. 70 a year earlier and an average 82 days in 2012-2017. This is the slowest end-of-summer market in four years.

Local home seller’s quick loss of market power is likely due to high homes prices and rising mortgages rates. By one metric, the number of Southern California’s “affordable” homes has been at least halved in five years.

Here’s how ReportsOnHousing broke down the slowdown by county …

In Los Angeles County …

Supply: 14,678 listings, up 2,681 residences for sale in a year or 22 percent; and up 9.9 percent vs. 6-year average.

Supply, year-to-date: Up 6,629 listings vs. a rise of 2,299 a year earlier and a an average increase of 3,878 in 2013-2017.

Demand: 4,939 new escrows, down 654 sales contracts in 12 months or 12 percent.

Market time: 89 days vs. 64 a year earlier and an average 74 days in 2012-2017.

In Orange County …

Supply: 7,207 listings, up 1,714 residences for sale in a year or 31 percent; and up 15 percent vs. 6-year average.

Supply, year-to-date: Up 3,647 listings vs. a rise of 1,259 a year earlier and an average increase of 2,335 in 2013-2017.

Demand: 2,167 new escrows, down 353 sales contracts in 12 months or 14 percent; and down 18 percent vs. previous six years.

Market time: 100 days vs. 65 a year earlier and an average 78 days in 2012-2017.

In Riverside County …

Supply: 9,171 listings, up 1,499 residences for sale in a year or 20 percent; and up 7 percent vs. 6-year average.

Supply, year-to-date: Up 1,667 listings vs. a dip of 1,386 a year earlier and a gain of 384 averaged in 2013-2017.

Demand: 2,545 new escrows, down 211 sales contracts in 12 months or 8 percent.

Market time: 108 days vs. 84 a year earlier and an average 97 days in 2012-2017.

In San Bernardino County …

Supply: 5,867 listings, up 654 residences for sale in a year or 13 percent. It’s up 10 percent vs. 6-year average.

Supply, year-to-date: Up 1,831 listings vs. a rise of 615 a year earlier and a an increase of 1,152 in 2013-2017.

Demand: 1,952 new escrows, down 255 sales contracts in 12 months or 12 percent.

Market time: 90 days vs. 71 a year earlier and an average 85 days in 2012-2017.