Most San Franciscans will hole up with Netflix and hot chocolate on a rainy day, so if you have some shopping you want to get done, you will pretty much have the area to yourself. Union Square and Westfield Centre tend to be the most popular shopping areas, but there are plenty of other spots to get your shopping fix. The Ferry Building is another wonderful place to spend a rainy afternoon, as the enclosed building offers shelter from the rain as well as a variety of local shops selling wares from glass candle holders to vegan donuts.
The Aquarium of the Bay is located right on the water, and while it is not a huge building, it has some beautiful exhibits, including tunnels that go through their Under the Bay habitat. The Exploratorium will bring out your inner kid, and the Legion of Honor will bring out your knowledgeable art critic.
It can be hard to get motivated to exercise in the rain, so do something a little different from your normal routine. Planet Granite, a climbing gym in the Presidio, is a great way to get exercise in while trying something new and different. Right next door is the House of Air, an indoor trampoline park where you can really shake up your routine.
There’s nothing better than beginning a new project on a rainy day, so why not try taking the creative route? Beyond Canvas offers everything from painting with wine (both as a drink and as a paint) to Shibori dyeing classes, which you can sign up for online. If you are looking for something edible, the San Francisco Cooking School has many classes that will truly immerse you in cooking and give you a better understanding for the kitchen.