Can you confirm whether you mean the GPS location for data tagging (commonly used to tag images taken with the phone's camera) or wether you are referring to the location detailed in the weather widget ?
Assuming you mean the location detailed within the weather widget, have the update settings changed to only update manually or is it still set to auto or X times per day ?
Have you recently been overseas on a foreign network or do you use T-Mobile which allows hopping across to the Orange network in poor areas of T-Mobile reception ?
Sometimes this happens in a particular area where the phone has the corrects settings but fails to receive the update, and sometimes it is due to related services on the phone not being active when you think they are. Typically "accounts and sycnhronisation" goes offline or resets to manual instead of automatic, which drags related services down with it.
Could be a bunch of underlying reasons but it would help a lot to know whether you mean GPS location (which can get a little screwy in certain areas) or if you mean the geographical location that your weather app should be using.
It's not normal, but it is quite common...