During which month does Lake Ontario generally reach its highest water temperatures?

Lake Ontario typically reaches its highest water temperatures in August. This phenomenon occurs due to a combination of factors, including seasonal heating from sunlight and the thermal inertia of the water. Throughout the summer months, particularly in July and August, the lake absorbs heat efficiently, and the effects of warming continue into August as long as there is sufficient sunlight and warmer air temperatures.

In June, the water is still warming, while by September, the cooler air temperatures and shorter daylight hours start to promote cooling in the lake. Thus, August represents the peak of seasonal warming, making it the month when water temperatures are generally at their highest.