Fog is the result of a dew point, that is when the humidity and temperature intersect to produce fog. The weather in general (temperature, wind, humidity,..) are not produced by a single variable. And San Francisco has the luxury of having a very nice temperature range which I continue to prefer over areas with regular temps below 30 degrees F and over 90 degrees. And for those that prefer warmer areas in SF, the eastern part is often 10 to 15 degrees warmer in the Summer. And of course the option for day, week and month trips are readily serviceable.