Each year, lightning strikes the United States approximately 25 million times, mostly during the summer. It claims the lives of about 20 people annually, according to the weather service. The threat of lightning becomes more pronounced as thunderstorms draw nearer, peaking when the storm is directly overhead and gradually waning as it moves away.

Hurricane Erin is expected to stay hundreds of miles off the East Coast, but its impact will be felt in the form of waves, wind and rip currents in Massachusetts this week.

While the rain affecting western Massachusetts on Wednesday is not linked to Hurricane Erin, the region is no stranger to the impacts of hurricanes and tropical storms during this time of year.

Sunday will be hot and humid across Massachusetts, with thunderstorms in the afternoon. Monday will see a big difference.

On his drive Thursday evening to the Planet Fitness in Dedham, Ryan Hynes was captivated by the scene unfolding outside. Darkness engulfed one direction, while the other shone startlingly bright. Gloomy and layered clouds moved fast across the sky. It seemed like it was about to downpour.