A record-breaking heatwave is forecast to grip much of the United States this Independence Day, potentially impacting celebrations marking the 250th anniversary of the nation’s independence. Forecasts predict temperatures nearing 50 degrees Celsius (122 Fahrenheit) in several Californian counties on July 4th. A large portion of the country is under a heat advisory, indicated by red alerts on weather maps. The extreme heat is already prompting adjustments to planned events, such as a shortened parade route in Philadelphia. Authorities are urging residents to take precautions against heatstroke and dehydration as the heatwave intensifies. This extreme weather raises concerns about public safety during the widely observed holiday.