The most remarkable thing about greater San Francisco is that, no matter what time of year it is, if you are going any significant distance, you will need if you are going to feel comfortable:
- A t-shirt,
- A long-sleeved shirt, and
- A sweatshirt.
Plus, in the rainy season you may well need an umbrella, a very good raincoat, rain pants, and rain, depending on where you are...