I have work boot galoshes like these ones, they slip on and off easily enough and are waterproof. I bought mine locally at a work boot shop for 30$, but you can sometimes get overshoes at Men's stores, they might be a bit much in hot weather but they'd be great in spring and autumn.

I ride on BMX pedals in the winter because I use massive sorel boots... the bmx pedals still grip even when my boots get snowy and icy... feet stay dry.