Travel like a European. They say, “There’s no bad weather, just bad clothing.”
Having the right gear makes riding in the rain no big deal. For most riders, that looks like using a rainjacket that they might wear anyway, and having fenders on their bike. If it’s raining really hard, maybe they have rainpants, a backpack cover, and waterproof shoes (or boots). The rainpants and backpack cover can be packed into a small pouch when not needed. It’s not a big deal to have the right gear for rain and hundreds of students bike and walk in the rain as it is still faster to do that than drive.
When it’s raining it can be more difficult to see. Having lights, reflectors, visible, and reflective clothing will help you be seen, safer, and following the law. Under California law, we need at least a white front light, rear reflectors, and side reflectors. Here is a great post by the Community Cycling Center in Portland, Oregon about riding in the rain. It rains a lot in Portland so they know what they are talking about.
Click the link or image to read the post.
And, if you are not ready to bike or walk in the rain, you could plan out who you might call for a rainy day carpool or plan to take the VTA bus. Here is the link to the VTA trip planner. Consider saving the link for later when you might need it.