J.J. Watt Harvey Relief Fund Passes $30 Million ... with Assist from Jimmy Fallon!

J.J. Watt's Hurricane Harvey relief fund is still goin' hard -- blitzing past $30 MILLION as Houston begins its long road to recovery.

After breaking $20 million on Tuesday, a couple HUGE donations came through for J.J. -- $5 mil from billionaire businessman Charles Butt and $1 mil from Jimmy Fallon and "The Tonight Show."

Fallon joins a long list of A-listers that have given big to Watt's fund -- including Miley Cyrus, Drake and Ellen DeGenerous.

Jimmy personally thanked the Houston Texans superstar on his show ... before giving the stage to a choir group from H-Town.

Awesome stuff.