Perfect fireworks weather, eh? Bf and I had that last year in western New York state, too.
But folks in my neighborhood have been setting them off for about two weeks, so... a few more tonight, for sure.
So yeah, definitely bring some warm stuff to BlogHer. If you're planning to check out the beach or Wharf, a leather jacket would not go amiss. Even on a nice day, it is windy by the water!!!
A few years ago the Burning Man newsletter, the JRS, said, "here in San Francisco, where it is 55 degrees year-round...", and I assure you, they were only partly joking. :P
Certainly this is a good amount warmer than our winter weather, with lows that occasionally dip into the thirties.