If you are using an older version of N2A's patched HTC Home Plugin then your weather stopped updating recently. You need a new version from the thread linked below.
http://forum.xda-developers.com/showthread.php?t=319187
Another option that worked for me was to delete the registry key below and then soft reset. The key below is created by older versions of N2A's modded HTC Home Plug to redirect weather to his server rather than accuweather's. If your city is not already in htc.accuweather.com then you must download a new version.
HKEY_LOCAL_MACHINE\Comm\Tcpip\Hosts\htc.accuweathe r.com
Some may experience issues with the registry changes not sticking. If you run into this issue, try hitting the power button and waiting a few minutes before resetting.