The Willow Warbler breeds throughout most of Europe north of the Mediterranean Basin and into Siberia. All birds winter in sub-Saharan Africa making for a migration journey of 12,000 kms for those birds that breed in eastern Siberia. See the distribution map at Birdlife International.

It looks very similar to Chiffchaff but has a bolder supercilium and more patterned face, lighter legs (usually browny-pink), with a lighter coloured yellow-pink to the sides of the bill and a distinctive song. A key difference is the length of the wings and the ratio of primary projection to tertials is noticeably longer than in Chiffchaff.