My Head Is My Only House Unless It Rains Lyrics

Lyric discussion by woodcut 

Cover art for My Head Is My Only House Unless It Rains lyrics by Everything but the Girl

I just asked my friends what it means that "my head is my only house unless it rains". I'm confused by that. Several friends said it means that she is secure in her head (her house) unless it rains (a storm comes by). The rest of the lyrics are amazingly beautiful, & I understand their meaning.

Anyone want to comment in 2011?

Song Meaning