Hello,
This is correct; weather in Command as currently implemented can change over time (e.g. clear day at noon, thunderstorms at night) but it remains constant over different locations at the same time. This is not a bug (which is why I would consider the term "fix" unsuitable) but a limitation of the current weather model.
As you can see on our public running poll (
http://www.matrixgames.com/forums/tm.asp?m=3437496), discrete weather fronts are a request fairly popular but less so than other features. So it is definitely on our development stack, but other items have higher priority at the moment.
Thanks!