Warning: the following is entirely my opinion and experience, and by no means should be applied generally.
Choosing a college in California, I (ignorantly) expected consistent and fairly warm weather, say around 70°F. However, I soon found how wrong I was.
While the weather in California may be much more moderate and consistent throughout the year, the weather in New York is much more consistent throughout each day. Here, I find the typical morning and evening chilly (arguably even “cold”) enough for a fairly thick jacket. Maybe I have yet to adjust to the Bay Area weather, but I even find myself having separate morning, midday, and evening outfits. In New York, while the summer tends to be brutally hot and humid and the winter tends to be quite cold (or “brick,” as we would say), the weather throughout the day is relatively constant.
I’ve also made the unfortunate discovery that the Bay Area weather changes much more often. I may check the weather forecasts in the morning to find that the high will be a moderate temperature, but then be surprised by a temperature in the 90s.
So, come prepared. Don’t be like me and end up needing your parents to mail you extra pairs of pants because you didn’t research the Bay Area weather enough.