It was formerly regarded as part of a wider "olivaceous warbler" species, but as a result of modern taxonomic developments, this species is now usually considered distinct from the eastern olivaceous warbler, Iduna pallida.

It is a small passerine bird, found in dry open country, including cultivation, with bushes or some trees.

The adults have a plain pale brown back and whitish underparts.

The sexes are identical, as with most warblers, but young birds are more buff on the belly.

The western olivaceous warbler occurs mainly as a passage migrant in southeast Morocco, although it also may breed in some densely vegetated areas there.