Rent prices throughout California's largest cities are on the rise, according to new data from the real estate site Trulia.

The data shows that San Diego, San Francisco and Los Angeles all had increases in rent prices during the month of December. And that rise isn't just confined to the state. Portland also had a 10.5 percent month-to-month average increase.

Why is this taking place now? And what does that market mean for homeowners and potential renters?

For more, we're joined by Stuart Gabriel, Professor of Finance and Director at the Richard S. Ziman Center for Real Estate at UCLA.