Wellington Boots are a Muggle item. However, they appear to be in use by wizards as well, as several pairs can be found at The Burrow.
From the Story
Discovered in Book 2, Chapter 3, The Burrow, Moment 2, The Weasleys'
"Wellington boots are waterproof rubber boots. The Weasleys own several pairs which lie in a jumble around the front door. They are named after the first Duke of Wellington, who popularised their use."
Click to go to Book 2, Chapter 3, The Burrow, Moment 2, The Weasleys'