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.
NEW INSTRUCTION.. FIND THIS FOLDER IN YOUR REGISTRY USING A REGISTRY EDITOR
HKEY_LOCAL_MACHINE\Comm\Tcpip\Hosts\htc.accuweathe r.com
OPEN THE FOLDER, YOU WILL FIND A COUPLE OF LINES..ONE OF THEM WILL LET YOU DELETE IT... DO SO.. CLOSE THE EDITOR AND SOFT REBOOT YOUR PPC ...THE WEATHER WILL WORK INSTANTLY NOW.
PUT THIS INSTRUCTION PARAGRAPH ON A TEXT DOCUMENT AND NAME IT WEATHER FIX AND PUT IT SOMEPLACE ON YOUR HARD DRIVE AND COPY IT TO YOUR STORAGE CARD FOR FUTURE USE. ALSO MAKE SURE YOU HAVE A CAB FILE OF THE REGISTRY EDITOR IF YOU DO NOT HAVE IT PERM. INSTALLED IN THE ROM ... PUT THE CAB IN YOUR STORAGE CARD TOO..
( THIS IS ALL FOR NEWBIES...)
Some may experience issues with the registry changes not sticki
ng. If you run into this issue, try hitting the power button and waiting a few minutes before resetting.