Getting a place like that last-minute in SF is going to be very difficult. It's difficult enough finding apartments in SF even if you plan ahead. +1 to CouchS

Getting a place like that last-minute in SF is going to be very difficult. It's difficult enough finding apartments in SF even if you plan ahead. +1 to CouchSurfing and AirBnB. Just keep an eye on Craigslist. If you don't work in the city proper, consider living outside of the city. Emeryvill and Berkeley are good bets. Be weary of Oakland as some parts are sketchy and unsafe. South Bay has several cities too but that may end up being pricey.