The middle of summer is here, and as to no surprise we’re tracking potentially the hottest temperatures of the year this week across much of the nation. Record-breaking heat will be possible as highs surge into the 90s and 100s for millions over the course of consecutive days. According to the National Weather Service, about half of the country is currently forecast to experience highs of at least 95 degrees within the next seven days.
The heat is already being felt this Wednesday. Heat Advisories are in effect for a large chunk of the central US in addition to the Mid-Atlantic coastal region. There are also Excessive Heat Warnings in effect for some of the bigger cities, meaning that the heat will be even more extreme for the urban areas. These areas include Philadelphia, Kansas City, Des Moines, Oklahoma City, and St. Louis. In the Ohio River Valley, there is also a large swath of Excessive Heat Watches in effect, hinting at the dangerous temperatures that’s to come there.
So why exactly is this heatwave occurring?
Well, there is a building ridge of high pressure over the eastern two-thirds of the nation. These large domes of high pressure in the mid to upper levels of the atmosphere typically lead to extreme heat in the summertime and are responsible for sinking air, a heating and drying mechanism. Therefore, conditions will generally be dry under this ridge. There will also be a strong surface high off the East Coast, which is often called a “Bermuda High.” Located near Bermuda, the clockwise rotation of these highs aid in bringing the heat and humidity in from the south and up the East Coast of the US.
This Wednesday, there will be two hot spots across the country: the central Plains and the East Coast. Widespread high temperatures in the 90s and 100s will be very common, with temperatures 5-10 degrees above average. Now while that doesn’t sound like much, it is actually very significant. Summer is the hottest time of the year for the US, so normal temperatures are already hot. When those temperatures go above normal, it can become dangerously\ hot.
By Thursday, the heat will really build and become more widespread across the central US as temperatures fall slightly on the East Coast. Temperatures will even dip slightly below average in New England due to the cloud cover and scattered showers from the remnants of Hurricane Barry. From the Texas Panhandle through the Great Lakes, temperatures will be 5-15 degrees above average, translating to actual highs in the mid 90s to mid 100s. Highs in the 90s will also be seen in Philadelphia and locations south of there.
The heat wave will really get cranking in the Northeast on Friday, marking the start to a brutally hot weekend. Temperatures in New England will rise by 10-20 degrees compared to Thursday’s highs. Most places in this region will experience high temperatures near 90 degrees, with the exception of Maine. The 90s will also be widespread from the deserts in Southern California through the Southwest and into the central and southern Plains, Midwest, and the East Coast. Highs will even rise into the 100s for a few hours in parts of the Plains and Mid-Atlantic.
Saturday by far looks to be the hottest day for the East Coast, with temperatures up to 15 degrees above average. About a dozen daily record high temperatures may be in jeopardy of either being tied or broken in the Northeast. New York City, Philadelphia, Washington, DC, Hartford, and Richmond may all reach or even exceed the 100 degree mark. Combine that with the high humidity, and that’s a deadly combination. Heat indices or feels-like temperatures will be between 105 and 115 degrees for most locations in the Northeast Saturday. Across the rest of the nation, temperatures will be about the same as they were on Friday.
By Sunday, temperatures will cool off slightly, but it will still certainly be hot. Thankfully, this will be the last day of this stretch of gruesome heat. Temperatures will decline across most of the eastern US, especially the central Plains and Midwest, as a dip in the jet stream ushers in below average temperatures. From the West Coast, where temperatures are beginning to increase, through the southern Plains and into the East Coast, temperatures will mainly be in the 90s for highs. The humidity will also remain high, meaning that feels-like conditions will be near 10 degrees warmer than the actual air temperature.
By early-next week, most locations will thankfully get to say good bye to the extreme heat and welcome the near to even below average temperatures and drier air.