Stay Dry - Get some wet weather kit. A waterproof hat with a rim allows more movement than a hood. Wellies are fine for most garden duties, but, for carrying heavy items or digging, walking boots offer more protection. For quick dashes it's worth keeping a pair of plastic clogs by the back door.
In her article Liz Dobbs makes no mention of gnome etiquette; we must assume, therefore, that leaving garden gnomes out in all weathers is discretional.