The severe weather posed risks to the large crowds gathered at the National Mall for the July Fourth celebrations. Potential hazards could include strong winds, lightning, or heavy rain, which are common during summer storms in the region. Such conditions can lead to injuries, property damage, and disruptions to planned events. The advisory to seek shelter was a precautionary measure to minimize risks to public safety. Attendees were likely affected by delays or cancellations of scheduled activities, including fireworks and speeches.