Yes. Lightning can travel for many miles to the side of its originating thunderstorm. This is sometimes referred to as A Bolt From The Blue, because the lightning appears to drop out of a clear, stormless sky. In reality, it's simply travelled from a host thunderstorm that's so far away, you can't see or hear it. But while lightning has been known to travel as many as 90 miles horizontally, most sideways strikes travel 1 to 10 miles and are usually the result of a storm you can hear in advance. So if you hear thunder, lightning is possible (even if it's not raining and you cannot see the storm) and it's important to take cover quickly.
---David Murphy
