I do enjoy getting caught in the rain from time to time, but prefer to not be caught sans umbrella.
Lesson #8: Prepare for anything. Just buy a big bag and before leaving each day, make sure to prepare for any type of weather/event/whim. Sure, you'll probably look homeless, but at least you'll be dry and homeless looking.
I'm not advocating bringing heels with you in case you find yourself needing to look fancy (well, unless it's the weekend. Then I might advise this), but more of your daily necessities. For instance, I often bring a snack with me because I don't know if I'll be hungry at some point, and a hungry me = an unhappy me. Plus it is sometimes hard to find vegan food around, though arguably easier here than anywhere in the country.
Other things that would come in handy to carry on a daily basis:
Book (obviously good for commutes. Or if you're eating alone and don't want to look really alone or something.)
Floss (I don't actually carry this, but I should. Days have been ruined by the agonizing feeling of something caught between teeth.)
Bandaids, in case you get blisters while walking. Or in case you get bloody nipples (wait, maybe that's just for marathon runners? hmmmm. Happy that I've never experienced this.)
Snack, umbrella, sweater (the necessities)
The list could go on and on, but just bring more than you think you'd want. Then in case you can't make rent and indeed are homeless, you'll have lots of cool things to do to pass the time.