Just in case you didn't know, there is a little more to the weather in the notification screen. I stumbled upon it by accident shortly after updating to iOS 5. Ever wonder why Apple doesn't give you every single detail? I do. But I guess it is also fun to discover new things as well.
If you have your local weather turned on in notifications, when you swipe down you will see today's forecast. I have mine at the top (you can customize your notification view). If you tap your local weather, you are brought to another screen that shows the extended forecast (5 days). Tap on the current day and you will get an hourly forecast for the next ten hours.
If you have any other cities you would like to add, click on the i in the bottom right side of the screen and add the new city. When you are done you can swipe to the right to see the additional cities added to included hourly weather and the extended forecast.