Unrelatedly, I'm still trying to figure out why Apple requires me to unlock my phone to look at the weather. Is there some concern that someone could pick up my phone and learn what city it is in?
You want to be able to launch apps without unlocking your phone? Slippery slope.
You can use the weather widget on the lock screen, and as long as you have lock screen content when locked enabled, you can see the current area's weather just fine. Or do you want the whole app experience?