I grew up in Seattle and so rarely used umbrellas as a kid. The rain there tends to be drizzly and light most of the time, so going out without an umbrella is fine. In NYC, though, the rain can come down so fast and so heavy that your clothes will be quite literally soaked through if you walk just a block or two: like you jumped in a pool fully dressed. It would be ridiculous to try to get by without an umbrella!
I hope you feel better!