America’s 250th anniversary also marks the final stage of the most intense heatwave in the eastern United States in years (made worse by climate change), which could further increase the threat of storms as the nation gathers to celebrate.
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Dangerously hot weather is on the guest list for every Fourth of July in this region, with highs of 90 degrees and lows of 100 degrees expected from New England to the Southeast. Major cities such as Philadelphia and Washington, D.C., are expected to experience triple-digit temperatures for the third day in a row on Saturday. Temperatures broke or reached daily records in at least 22 locations on Thursday, and 17 more locations experienced colder temperatures on Friday.
Here are the heatwave headlines:
• Heat stroke and death: A 68-year-old man died after mowing brush on July 2 in Bethel Township, Pennsylvania, where temperatures exceeded 100 degrees, the Berks County Coroner’s Office told CNN. The cause of death was a heart attack caused by overexertion “due to heat exhaustion,” the agency said. Meanwhile, the CDC reported Thursday that areas across the Northeast are experiencing “very high rates of heat-related illness.”
• Events canceled or delayed: The Fourth of July parade scheduled for Saturday morning in Washington, D.C., has been canceled due to the extreme heat in the nation’s capital. President Donald Trump’s Great American State Fair opens two hours later at 12 p.m.
• New York City power outage: Thousands of customers in the New York metropolitan area lost power Friday, according to local power company Con Edison. Some outages were shut down to prevent extended outages. Parts of Staten Island, Queens, the Bronx, Brooklyn and Westchester also experienced brownouts earlier in the day, Con Edison spokeswoman Jamie McShane told CNN.
• Air Quality Warning: A dome of intense heat lingers over the eastern United States, potentially exposing millions to twice the effects of unhealthy air. From formal rocket shows to impromptu celebrations in the streets, fireworks can cause extremely unhealthy atmospheric conditions, sometimes comparable to wildfires. In some cities, air quality often does not return to normal until around noon the next day.
Thunderstorms could be another uninvited guest this Independence Day. Extreme heat and humidity will increase the threat of storms across parts of the Mid-Atlantic Coast and Northeast starting Saturday afternoon.
Some of these storms bring strong wind gusts, but thunderstorms also contain lightning, which is a great danger for outdoor activities, especially for those trying to escape the heat in or on the water. The fireworks display may be canceled due to inclement weather.
Storms with damaging wind gusts of 60 miles per hour or more are most likely to occur in the easternmost part of the Level 2/5 danger area on the map below.
There is one silver lining. Thunderstorms to the east Saturday are expected to be more random rather than widespread and organized. That means areas affected by the thunderstorms may eventually see enough weather to resume festivities.
Behind a heat wave is a powerful thermal dome, a stagnant region of high pressure that traps and intensifies hot, humid air. But human-induced climate change caused by fossil fuel pollution is making this familiar summer weather pattern even more dangerous.
Saturday’s high temperatures are expected to be only slightly cooler than Thursday and Friday’s temperatures as the hot dome continues.
When the Founding Fathers signed the Declaration of Independence in 1776, the high temperature in Philadelphia was 76 degrees. Thomas Jefferson himself recorded that measurement. It was a peaceful day at the time, but 250 years later, the city is completely deserted.
High temperatures are expected to reach 100 degrees in Philadelphia on Saturday, and the heat index (how the air actually feels on your body, taking into account humidity) will be several degrees higher than the actual temperature.
Washington, D.C., also recorded triple-digit highs, potentially marking the hottest Fourth of July day ever on record.
New York City is expected to see highs in the low 90s after recording triple-digit temperatures Thursday and Friday, but the heat index will still make the city feel like the triple-digit temperatures are gone.
The heat will begin to ease in much of the East on Sunday, with highs expected to return to the more seasonal 80s next week. However, temperatures in parts of the Southeast will remain in the 90s for much of next week.
Since Thursday, heat in the East has broken at least 30 single-day high temperature records and numerous warmest and coldest temperature records as some cities reached levels not seen in more than a decade.
New York City’s Central Park reached 100 degrees Thursday afternoon for the first time since 2012, tying the record for highest temperature on that day.
Temperatures in Washington, D.C., soared to 102 degrees on Thursday and Friday, breaking a daily record that had stood for more than 120 years. Philadelphia recorded a high of 103 degrees on Thursday, tying the record set in 1901.
This week’s intensity of heat and humidity would have been “virtually impossible” without the influence of fossil fuel pollution. The findings were released early Friday by World Weather Attribution, a scientific network that analyzes the role of climate change in causing extreme weather events.
Friederike Otto, professor of climate science at Imperial College London, said: “When a historic Independence Day celebration is interrupted and World Cup matches are played in conditions that are dangerous for players and fans, it shouldn’t take new scientific research to wake people up.”
“Climate change is here, it’s already affecting what we enjoy in our daily lives, and the longer the inevitable transition to net-zero emissions drags on, the worse it will continue to get.”
