Born outside Baltimore, Brennan began composing for chamber ensembles in his teens. After studying poetry at college, he began working at a studio in his hometown, producing music for television, radio, and theatre. In 2011, he relocated to Brooklyn where he currently lives with his wife.
Brennan has been diagnosed with a rare genetic eye disease called Choroideremia, and he is gradually going blind. After a few years of accelerated vision loss, in summer 2014 Brennan moved to the beach near Assateague Island, Maryland, where he built a studio and began work on a full length album, Suspending Disbelief. The first single, “Coaccidents”, was released in May 2019, and won First Prize in the Great American Songwriting Contest.
In 2017, “Little Bit of Light” was used by GEICO in their Motorcycle campaign. Strange Weather has expanded into a rotating cast of characters that includes Callie Brennan, Davis Rowan, Paul Peglar, Sarah Mount, Matt Tobin, Slark Moan, Dan Drohan, Meia Noite, Yula Beeri, and Avram Fefer.