Why is there a heatwave in the Northeastern and Central US?

As of July 15, 2024, there is a heatwave in the Northeastern and Central United States primarily due to a persistent high-pressure system and upper-level ridges that are trapping heat in the region (1)(2).

This weather pattern prevents cooler air from moving in and keeps temperatures significantly higher than the historical averages. Additionally, high humidity levels exacerbate the heat, making it feel even hotter and increasing the heat index values.

The heatwave is influenced by broader climate patterns, including the increased frequency and intensity of heatwaves linked to climate change. These patterns result in more prolonged periods of extreme heat, as seen in the current situation.

Temperatures are expected to rise above the historical average for much of the Northeastern U.S. through Tuesday (3).

Which cities or areas are affected by the heatwave?

The heatwave spans a broad swath of the United States from the Plains to the East Coast, covering the Midwest, Southeast, Ohio Valley, and the Northeast. This extensive heatwave impacts urban areas where the combination of concrete, asphalt, and limited green spaces can amplify the heat effect, known as the urban heat island effect.

In turn, the rising heat is impacting air quality in the Northeast and Midwest where there is widespread “moderate” air quality.

Impacted cities include:

• Baltimore, Maryland
• Boston, Massachusetts
• Charleston, South Carolina
• Charlotte, North Carolina
• Cincinnati, Ohio
• Dallas, Texas
• Indianapolis, Indiana
• Miami, Florida
• New Orleans, Louisiana
• New York City, New York
• Philadelphia, Pennsylvania
• Raleigh, North Carolina
• St. Louis, Missouri
• Washington D.C.

These regions are experiencing record-breaking temperatures and high humidity, contributing to dangerous and potentially deadly heat conditions.

How long will the heatwave last?

The heatwave started in the western U.S. and has now moved eastward. It is expected to continue through at least Tuesday, July 15, 2024. The duration from its onset to its expected end is about two weeks.

Are there any alerts in place?

Yes, there are several alerts and warnings in place (4):

• Excessive Heat Warnings/Watches: Covering parts of the Mid-Atlantic, New England, Central/Southern Plains, Middle/Lower Mississippi Valley, and Western Ohio Valley.
• Heat Advisories: Issued for numerous urban centers in the affected regions.

Residents are advised to seek cooling centers and stay hydrated. Special caution is urged for vulnerable populations such as the elderly, children, and those with health conditions.