As shown on a great website called http://nyfalls.com, fall is a great time to visit niagara on the lake and many events are happening....here are several the site highlights
Canal Days. 
(Early August - Port Colborne, ON) - The Canal Days Marine Heritage Festival offers activities and attractions that will enliven the senses. The Tall Ships gather in Port Colborne each August holiday weekend for a four-day celebration of history and heritage. Explore the decks, try your hand at the wheel, or feel the spray as you cruise a Tall Ship on Lake Erie.
http://www.canaldays.ca/page/canal_days
(Early August - Port Colborne, ON) - The Canal Days Marine Heritage Festival offers activities and attractions that will enliven the senses. The Tall Ships gather in Port Colborne each August holiday weekend for a four-day celebration of history and heritage. Explore the decks, try your hand at the wheel, or feel the spray as you cruise a Tall Ship on Lake Erie.http://www.canaldays.ca/page/canal_days
Artful Weekend. 
(Early August- Niagara Wine Trail in NY) -Browse and enjoy the work of local artists and craftsman at each winery on the trail. Your $20 ticket includes a wine tasting at each winery and a commemorative wine glass.
http://www.niagarawinetrail.org
(Early August- Niagara Wine Trail in NY) -Browse and enjoy the work of local artists and craftsman at each winery on the trail. Your $20 ticket includes a wine tasting at each winery and a commemorative wine glass.http://www.niagarawinetrail.org
Royal Canadian Henley Regatta. (Early August - St. Catherines, ON) - Since the "Henley" settled in St. Catharines in 1903, it has grown to become the largest of its kind in North America. In 2007, over 2,700 men and women from over 150 rowing clubs competed for Henley Gold.
http://www.henleyregatta.ca
(Early August - St. Catherines, ON) - Since the "Henley" settled in St. Catharines in 1903, it has grown to become the largest of its kind in North America. In 2007, over 2,700 men and women from over 150 rowing clubs competed for Henley Gold.http://www.henleyregatta.ca
Siege Weekend at Old Fort Erie. (Early August - Fort Erie, ON) - A weekend of historic siege battle reenactments and demonstrations at the Old Fort Erie historic site.
http://www.oldforterie.com
(Early August - Fort Erie, ON) - A weekend of historic siege battle reenactments and demonstrations at the Old Fort Erie historic site.http://www.oldforterie.com
Historic Lewiston Jazz Festival. (Late August - Lewiston, NY) - Jazz musicians will perform throughout the village of Lewiston, NY in numerous restaurants and lounges -- as well as at a variety of outdoor sites along Center Street. Also featured: jewelry show and vintage car show.
(Late August - Lewiston, NY) - Jazz musicians will perform throughout the village of Lewiston, NY in numerous restaurants and lounges -- as well as at a variety of outdoor sites along Center Street. Also featured: jewelry show and vintage car show.