Big ones in recent memory:

• 1992, Andrew – Formed August 16, Dissipated August 28
• 2005, Katrina – Formed August 23, Dissipated August 30
• 2011, Irene – Formed August 20, Dissipated August 29

Very narrow window at the end of August.

And you may not think that Irene was a big deal, but the damage is already at about $20B.