International & cosmopolitan cities like San Francisco rarely experience major downturns (most local SF real estate agents will cite 1989-1991 as the last one) and are usually the last to the party and the first to leave. In other words, a real estate market downturn in San Francisco is rare and doesn't last long relative to most of the country.
Personally, my belief is that 2009 was the bottom. Time will tell. My crystal ball may be a little better than the average person's simply because I work in the housing trenches day in, day out and pay attention to micro-trends but it's not omniscient.
Our local San Francisco Board of Realtors just published their latest market data report. SFAR tries to keep ahead of State and National reports because all real estate is local and our market is pretty unique.
Here's a highlight of the latest report.
"Sales activity in San Francisco’s housing market rebounded during the second half of 2009 and into early 2010, resulting in a significantly tighter housing market from a year ago, according to the most recent Market Focus report released jointly by the Rosen Consulting Group and the San Francisco Association of REALTORS®. The report states that completed home sales in March 2010 increased 58 percent from the same month a year ago, absorbing much of the excess inventory in the market and intensifying competition among buyers for desirable properties."
Check out the full report as a PDF File on San Francisco Real Estate and corresponding press release from the San Francisco Real Estate Board:
Market_Focus_Report_April_2010