The housing market across Southern California continued to slow last month as home sales had its weakest January in 11 years, according to data released Wednesday by CoreLogic.

The real estate research firm reported 12,665 homes and condominiums changed hands in January, a 17.1 percent decline from 12 months ago and 19.8 percent fewer sales than December. Last month was the weakest January since 2008 when the housing bubble across the region had just fractured.

Sales have declined year over year for the last six months and in eight of the last 10.

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In the four-county area, the steepest sales declines in the last 12 months were in Orange County, at 20.3 percent and Riverside County, at 16.8 percent. Los Angeles and San Bernardino counties declined 15.8 and 13.1 percent, respectively.

CoreLogic analyst Andrew LePage said the slowdown likely can be traced to affordability issues, stock market volatility, December’s federal government shutdown and concerns the housing market had peaked.

High-interest rates in November also had buyers balking, said Robert Kleinhenz of Los Angeles-based Beacon Economics and a former deputy chief economist for the California Association of Realtors. Three months ago, when mortgage rates peaked at 5 percent, potential buyers either could not qualify for a loan or made a decision to back out of the market.

With rates down to 4.32 percent, the market trend could shift upward, Kleinhenz said.

“Now we’re heading into the busy season for home sales, and we may end up with a 2019 market that does as well as, or maybe a little better than, it’s been doing,” he said.

The glacial pace of new homes sales last month was 57.9 percent below the January average spanning the last 31 years. That tugged on sales for all homes, with Los Angeles County tumbling 22.9 percent, Orange County off 21.4 percent, Riverside County down 20.8 percent and in San Bernardino County sliding 7.6 percent.

The market could stabilize because more sellers in affordable price ranges are coming to the market, said Jenny Segovia, an agent whose handles listings in the $300,000 to $500,000 range in South Central Los Angeles and the San Fernando and Antelope valleys.

Segovia said more inventory in the last few months has given buyers some leverage.

“Now we’re seeing some sellers paying for closing costs and repairs, and some are even dropping their prices,” Segovia said.

January’s median price of homes for all Southern California homes was $505,000, down 1.9 percent from December. Prices were up 2 percent year over year, which is the second-lowest gain — barely ahead of December’s 1 percent increase — in almost seven years.

Prices were flat from December to January in Riverside County, the only county in the region that did not lose ground. Prices fell 0.3 percent in Los Angeles County, 1.2 percent in Orange County and 3 percent in San Bernardino County.

In the last 12 months, prices rose 2.7 percent in Riverside County, 2.6 percent in Los Angeles and San Bernardino counties and 1.4 percent in Orange County.

The median Orange County home sold for $700,000 last month; $579,500 in Los Angeles County. In the Inland Empire, the median sales price was $380,000 in Riverside County and $320,000 in San Bernardino County.

Yvonne Mendez of First Team Real Estate’s Corona office said she had seen a slowdown but said more inventory should help level out the market.

“Prices may not increase, but I think we are moving towards a neutral market in some areas,” Mendez said.