Spain is in three hemispheres: the Northern Hemisphere, the Eastern Hemisphere and the Western Hemisphere. The Prime Meridian, which divides the Eastern and Western Hemispheres, runs right through eastern Spain, which puts the country in both hemispheres simultaneously.
According to About Geography, Spain is more unambiguously in the Northern Hemisphere, which starts at the Equator. The Canary Islands, a Spanish archipelago just off the west coast of Africa, also lies in the Northern Hemisphere, although it is closer to the Equator than the Spanish mainland. In the past, when Spain had a worldwide empire, it had colonies and territorial holdings in all four hemispheres.