not all icons are black.. some.. depending on the weather forecast..
if you need an all white icons, I don't have it..
if you found a suitable icons, put it into this folder AveDesk\Docklets\SysStats\icons\
you can change by configuring it (right click > configure)
go to overlay tab, select weather icons, click 'configure', change path. make sure it also ends with %s.png