@Suty I've done a bit more search and found another thread on this forum that actually has the fix: https://community.windy.com/post/122223

When setting the gfx.color_management.mode option to 1 this causes the bug. Resetting it to 2 (the default) fixes it. It's not really ideal to disable that given it's needed for colour accurate rendering.

I'm not sure why that thread didn't show up when I searched before.

Thanks for your assistance.

@TheRadarGuy Enabling that option make things even worse:

I have a lot of things set in about:config, but a quick look through them didn't throw up anything obvious. Anything in particular I should be looking for.

Firefox is up to date (v123). Opening it in a private tab causes the same issue. However starting FIrefox with a new profile causes it to start working, which indicates there's something about my setup.

It seems windy isn't loading the wind data correctly in Firefox as it's always blowing the same direction, at a few million km/h (changes depending on the location clicked) which is...a bit much:

I've tried clearing the cache, deleting all local data, disabling adblock and enhanced tracking protection, nothing seems to fix it.