Firefox will NOT work for weather.com

What does that mean? Show the issue by posting screenshots showing the problem. Windows home or pro? What security software are your running besides MS Defender?

It worked a month ago before some firefox upgrades. It cycles over & over again briefly displaying "Transferring data from weather.com ...." in the bottom left corner status window. Nothing else but a blank screen! so a screenshot is useless to show you a blank screen

Okay... Did you try with firefox in troubleshoot mode?

Running the latest McAfee but that has worked for 10 years with the site. latest win10 pro

yep same in troubleshoot mode

A few test... You can disable mcafee, reboot, and try again. Boot windows into safe mode with networking and test. Windows pro, you can run Windows Sandbox for testing. https://www.howtogeek.com/399290/how-to-use-windows-10s-new-sandbox-to-safely-test-apps/ You can also refresh firefox.