While you can conceivably work on scaffolding in inclement weather, it's typically not a safe practice. It's easy for workers to slip on wet platform surfaces or accidentally drop tools on passersby far below. Heavy winds could blow unsecured scaffolding equipment over or cause workers to lose their balance.
It's better to avoid scaffolding work in bad weather or when any other potentially adverse situations exist. You should also remain alert throughout the workday for changes that could cause working conditions to deteriorate.