Plomodiern (; ) is a commune in the Finistère department of Brittany in north-western France.
Plomodiern has an oceanic climate (Köppen climate classification Cfb). The average annual temperature in Plomodiern is . The average annual rainfall is with December as the wettest month. The temperatures are highest on average in July, at around , and lowest in February, at around . The highest temperature ever recorded in Plomodiern was on 9 August 2003; the coldest temperature ever recorded was on 13 January 1987.
Inhabitants of Plomodiern are called in French Plomodiernois. The village is located next to the Menez Hom.
2020: