The Lake Michigan effect
When the land warms up during the day, a strong temperature gradient establishes itself between the lake and land. This gradient sometimes forces a lake breeze to develop. What happens is the air over land heats up and rises, thus making way for the cold air that sits over Lake Michigan. That cold air gets pushed inland as a result of the lake breeze. As a result, temperatures along the coast and even several miles inland fall.Typically, lake breezes develop once the land warms up enough during the day. This occurs during the early afternoon hours in most instances. For example, the temperature in Benton Harbor can warm to 75° by 1 PM on any given day, but once that happens, a lake breeze can develop and cause that temperature to drop as much as 10-20° by the late afternoon and early evening hours. These lake breezes can develop during the spring and summer months, but are most common from March and April through the first half of July. This is because the water temperature during this period is much colder than the land temperatures. Of course, it isn't all bad. When a lake breeze develops on a day in which temperatures soar into the mid-90s, the beach is usually a popular destination. That's because the temperatures along the immediate shoreline are in the lower 80s, if not cooler!