Central Florida is in the grip of a blistering heat wave as a massive “heat dome” intensifies temperatures across the region. On July 29, the National Weather Service issued an Extreme Heat Warning for Volusia, Lake, Orange, Seminole, and Osceola counties, with heat index values soaring between 110°F and 115°F. This marks only the second time in history such a warning has been issued in the Orlando area, the previous being in August 2023.
Multiple cities broke or tied previous heat records. Sanford hit 100°F, Leesburg reached 99°F, and Daytona Beach tied its 1992 record of 98°F. Even Orlando came close to its 1949 record at 98°F. A Heat Advisory remains in effect through midweek, and while isolated thunderstorms may bring temporary cooling, meteorologists warn that high humidity under the heat dome will continue to exacerbate dangerous conditions.
Philadelphia Faces Dual Threat of Heat and Air Quality
Philadelphia is also enduring one of its most severe heat stretches of the summer. On July 29, the city tied its 2002 temperature record at 98°F, with a similar high expected again on Wednesday. With humidity factored in, the heat index is expected to surpass 105°F, placing millions at risk of heat-related illnesses.
In addition to the extreme heat, the Pennsylvania Department of Environmental Protection issued a Code Orange ozone alert, urging children, seniors, and individuals with respiratory issues to avoid outdoor activity. Residents were asked to reduce pollution by limiting driving and conserving electricity.
A brief reprieve may come Thursday as a cold front triggers scattered thunderstorms. By Friday, daytime highs could dip to the mid-70s°F, with nighttime lows in the 60s and 50s, ushering in a much-needed cooldown across the region.
Eastern U.S. Braces for Heat’s Peak Before Canadian Cooldown Arrives
The heat dome impacting Florida and the Northeast is part of a broader, nationwide weather pattern affecting over 170 million Americans. From the Deep South to the Great Lakes, cities are recording triple-digit temperatures and heat indices exceeding 110°F. Tampa saw its first 100°F reading in over 130 years, and Memphis, Atlanta, and much of the Southeast are experiencing similar extremes.
The heat dome has been particularly relentless overnight, with high humidity preventing temperatures from dropping significantly. This increases the risk for vulnerable populations, especially without access to air conditioning.
However, relief is in sight. Meteorologists expect a major cooldown beginning Thursday, as a mass of Canadian air pushes across the northern U.S. By the weekend, cities from Chicago to Boston could see temperatures 10–20°F lower, with some overnight lows plunging into the 40s°F in the Northeast.
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