You might find it useful to bring a rainproof small back pack / purse / bag to carry your stuff while walking on the street, cause most probably you will find yourself under the rain. At least I was happy to have my rainproof (microfiber) backpack with me, as it kept my camera and other stuff from getting soaked! Same applies for your clothes... an umbrella won't be very useful with the hard rains you will have to face - especially in the summer - so you might want to take a raincoat with you instead. And if you wear some boots you might be lucky enough not to get your feet soaking wet while crossing the streets, which turn into RIVERS whenever it rains... I would have liked to have mine handy but I didn't take them with me! So don't forget them!