As Americans head outdoors to celebrate the nation’s 250th anniversary, millions of Americans across the eastern half of the country are facing an extended period of dangerous and potentially record-breaking heat.
The intense heat and humidity will spread across the Midwest early this week and move into the Mid-Atlantic and Northeast by Wednesday. A vast heat dome remains in the East, particularly over the I-95 corridor, and is expected to peak by Friday, in time for the Fourth of July long weekend.
Temperatures in many areas will continue to hover around or above 100 degrees Fahrenheit, while humidity is expected to push the heat index, or “feels like temperature,” above 110 degrees.
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Heat waves are becoming more intense and frequent around the world due to anthropogenic global warming caused by fossil fuel pollution. Record heat waves in Europe last week and in the western United States in March are two recent examples.
Heat is also the deadliest weather in the United States, causing more deaths on average each year than tornadoes, hurricanes and lightning combined, according to National Weather Service statistics.
The biggest concern is not only how hot it will get in the afternoon, but also that it won’t stop even after the sun goes down. Across a vast geographic region, the combination of several days of hot days and exceptionally warm nights poses a serious health threat.
More than 100 daily highs could be matched or broken this week alone, while more than 250 warm overnight lows could be challenged.
The message from the National Weather Service has been consistent: this heat wave is different. In eastern Virginia, the weather service said this heatwave could be the most severe in the region since July 2012, which caused more than 10 of the state’s more than 30 heat-related deaths in four states. Other forecast offices from the mid-Atlantic coast to New England are warning of an increased risk of heat stroke after several days of dangerous heat and unusually warm nights.
High temperatures in Richmond, Virginia, are expected to exceed 100 degrees for the third day in a row, approaching the city’s hottest July ever on record and potentially breaking daily records.
North Carolina is not expected to challenge Raleigh’s all-time high temperature record of 106 degrees, but overnight lows later this week could break the city’s all-time high of 80 degrees.
In Washington, D.C., Thursday’s high of 102 degrees and Friday’s high of 103 degrees could set daily records if the forecast holds, while nighttime temperatures could continue to exceed 80 degrees, threatening the record-warmest low. New York City could tie both the record for daytime high temperature on Thursday night and the record for overnight low temperature on Thursday night.
Future heat waves will also be widespread. More than 100 million people from the Deep South as far north as parts of Minnesota, Wisconsin, Michigan and Maine, and as far east as New York and Boston are at a Level 3/4 “severe” or Level 4/4 “Extreme” heat risk for one or more days this week, according to the National Weather Service.
The Bureau of Meteorology says such extreme heat can affect anyone without proper cooling and hydration. At night, high humidity causes your body temperature to rise, preventing sweat from evaporating efficiently and making it harder for your body to cool down, so there is little hope for symptom relief.
Low temperatures will not dip below the low to mid 70s in the Midwest and Great Lakes this week. In urban areas, where concrete and asphalt absorb heat during the day and slowly release it at night, it can be difficult to get much below 80 degrees.
According to the Centers for Disease Control and Prevention, prolonged exposure to extreme heat can lead to illnesses such as heat exhaustion, heat cramps, and the most serious type of heat stroke. According to the National Weather Service, emergency room visits due to heat stroke spike on “severe” and “very dangerous” days.
The heatwave is expected to peak during the busiest travel and outdoor celebrations of the year. Millions of Americans attending parades, cookouts, sporting events, and Fourth of July fireworks should prepare for dangerous heat, especially during the afternoon and evening hours.
Parts of the Midwest and Northeast will see cooler temperatures and the potential for thunderstorms later in the weekend as the upper layer of high pressure weakens and moves westward. However, much of the South is expected to continue experiencing above-normal temperatures next week.
