A typical Southern California household’s ability to buy a house got slightly worse in most of the region at the end of 2016, according to one affordability index.

The California Association of Realtor’s measure of what it took to buy a local home in the fourth quarter shows three of four Southern California counties with falling affordability. This index tracks what share of households can afford a median-priced, single-family house.

Read: Exodus from California is a myth

Buying was more of a challenge for this benchmark house hunter as rising home prices and pricier mortgages outpaced income growth. By CAR’s affordability math, for the fourth quarter:

• Los Angeles County: It was the only local county with improving affordability, as 28 percent of households could afford to buy vs. 26 percent in the previous quarter and 27 percent a year earlier. At year’s end, an L.A. household must earn at least $99,230 to afford the typical monthly house payment of $2,480 on the $503,400 median-priced home.

• Orange County: The least affordable county in the region with 22 percent affordability vs. 23 percent in the previous quarter and 21 percent a year earlier. Households must earn $146,880 to comfortably pay house payments of $3,670 on the $745,160 median-priced house.

• Riverside County: Affordability fell to 41 percent vs. 42 percent in the previous quarter and 39 percent a year earlier. Households must earn $70,250 to comfortably pay the house payment of $1,760 on the $356,380 median-priced home.

• San Bernardino County: This is the region’s affordability hotspot at 54 percent vs. 55 percent in the previous quarter and 53 percent a year earlier. Households must earn $49,500 to comfortably pay house payments of $1,240 on the $251,100 median-priced home.

Statewide affordability in the fourth quarter was 31 percent, the same as the previous quarter but up a notch from 30 percent in 2015’s fourth quarter.

Least affordable counties? San Francisco (13 percent), San Mateo (15 percent) and Santa Cruz (17 percent.)

Contact the writer: jlansner@ocregister.com

ALSO: