Hurricane season runs June through November. Tropical storms can drop a lot of rain in a short time, and clogged gutters overflow right when you need them most. Heavy, waterlogged debris also adds weight, which strains hangers just as strong winds arrive. Cleaning before the season gives your gutters the best chance to carry water away and stay attached to the house.
After a storm passes, it is worth having the gutters checked again. Wind blows leaves, fronds and small branches onto the roof, and they often end up in the gutters and downspouts. Make sure your downspouts are clear and still connected, too.