Sarnia is about an hour west of London on the 402.
It is the largest city in Lambton County, where Lake Huron meets the St. Clair River, with the Blue Water Bridge across to Port Huron, Michigan. Chemicals and energy are its biggest industries. In summer the lakeshore gets busy: Grand Bend's population grows a lot, and Pinery Provincial Park has about 10 km of Lake Huron beach.
For a trades or service company in Sarnia, steady local ads all year usually make sense. A restaurant, shop or rental near the lake is different. It needs more budget from June to August, aimed partly at visitors coming from London and further away, and a smaller local campaign the rest of the year. We plan that calendar with you before anything is spent.