A significant heat wave is on the way, with an extended period of high temperatures and high humidity levels likely for much of the eastern half of the United States.
A dramatic weather pattern shift will allow for a Bermuda High to take up residence along the East Coast; the clockwise flow around this system will help draw warm and humid air from the Gulf north towards New England.
While hot and humid conditions aren’t rare for June, they are rare this year; an unusually cool and damp weather pattern has been stubborn to leave the Mid Atlantic and New England for much of the Spring.
The heat wave will stress the bodies of people and pets not used to the summertime conditions. In addition to rising temperatures, dewpoints will rise too. Technically, a dewpoint is the temperature below which water droplets begin to condense and dew can form. The higher the dewpoint as it relates to temperature, the higher the humidity is and the more uncomfortable it begins. In places like Philadelphia, PA, the dewpoints will rise from the upper 50’s on Saturday to the upper 60’s by Tuesday. The combination of high heat and humidity will create a high heat index. The heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature. When the body gets too hot, it begins to perspire or sweat to cool itself off. If the perspiration is not able to evaporate, the body cannot regulate its temperature. Evaporation is a cooling process; when perspiration is evaporated off the body, it effectively reduces the body’s temperature. When the atmospheric moisture content, measured as relative humidity, is high, the rate of perspiration from the body decreases. In other words, the human body feels warmer in humid conditions.