If you're looking at charts that show a spike in prices in only the past month, I assume you're referring to year-over-year prices, and possibly older Case-Shiller reports which is data that tends to be 3 months old. So literally you're looking at changes that have occurred over the past 15 months. Prices in the City, including the Castro, have been on the rise for at least a year and a half. The market has been on fire for that long.
There are four main reasons this has happened and if you can predict where these four things will be in the future you'll have an idea where home prices might be.
They are 1) jobs - San Francisco has been adding far more jobs than new housing inventory, and many of these are high paying tech jobs. We're closing in on the jobs peak hit during the height of the dot-com market.
2) the stock market is WAY up over these past 4 years with both the Dow and S&P past their previous peaks. This is important since many people pull their down payments from the stock market - and sometime pull enough for all cash purchases - and they can afford a LOT more than they could even a year ago
3) interest rates, while up from 2 months ago, remain at historical lows. This allows buyers who need loans to afford far more than they used to.
4) there is no inventory. In the Castro there are 6 total residential properties for sale (homes, condos, TIC's) right now. In the past 6 months only 86 have sold, or 7 per month.
So imagine a lot more people with high paying jobs, with far more cash thanks to the stock market, able to afford larger loans due to interest rates - ALL chasing 6 homes in the Castro.
So for now, I expect prices to rise until there are significant changes in 2, 3 or all 4 of the above. Two have had a bit of a change - interest rates are up, and the stock market is sputtering a bit, but neither have changed enough to overcome record low inventory being chased by numerous well healed buyers.
Since you mentioned wanting to buy in 6 months, I'd start today just by looking and getting pre-approved for a loan if you need one, and hoping for at least a little spike in inventory in Sept/Oct which will be your best chance to find something until after January.
You're welcome to start here if you like http://www.SF-MLS-Search.com