Rain, rain, rain
As in most port cities in Japan, rain comes hard and heavy with little warning. If you're here for a while invest in a decent umbrella as it can be VERY breezy at times. You will end up paying more by buying the cheap umbrellas that keep breaking than you would a decent one to start out with.

The ocean view from Yokosuka Museum
Nobori-gumo Onsen
Yokosuka