Lightning can be seen from up to 100 miles away if the horizon is clear and the clouds are high.

The Mystery of Silent Light: What Causes Lightning Without Thunder?

If you'd like to dive deeper into the science of summer weather: (the "Flash-to-Bang" method)

If you see flashes, a storm is likely within 100 miles.

If the flashes get brighter or the intervals shorten, the storm may be heading your way.

Thunder is a physical shockwave. As it travels, it interacts with different layers of air temperature. Sometimes, the sound waves are refracted (bent) upward into the higher atmosphere. This creates a "shadow zone" on the ground where the lightning is visible, but the sound literally passes over your head. Why Do We Call It "Heat Lightning"?