Extreme Heat Continues Into Wednesday

The dangerous heat dome of high pressure will soon begin to loosen its grip on the central and eastern U.S., following dozens of record highs from Boston to New York and Washington, D.C. The surge of muggy air will continue for many cities up and down the Interstate-95 corridor.

June and even all-time record heat has been observed the past few days in the Midwest and East. Plattsburgh, New York, hit 101 degrees Monday, tying its all-time record high for any day of the year. Go to this link for a rundown of some of the most significant records that have been set.

A high school graduation in Paterson, New Jersey, was canceled mid-ceremony Monday after several individuals were transported to hospitals for heat-related illness, while dozens of others were treated at the scene.

Weather in your inbox

Forecast Location

Sign Up

By signing up you agree to the Terms & Privacy Policy. Unsubscribe at any time.

(MORE: Download The Weather Channel App To Track The Heat Dome)

Here are the main takeaways from the forecast:

Heat Alerts

- The National Weather Service has issued extreme heat warnings and heat advisories from the Eastern Seaboard westward to the lower and mid-Mississippi valleys, as you can see in the map below.

- The highest level heat alerts are now called "extreme heat" warnings. You can find more about those changes here. These alerts indicate that heat illnesses are expected to spike when they are in effect and include Boston, New York City, Philadelphia, Washington, D.C. and Raleigh, North Carolina.

(TRACK THE HEAT: Temperatures | Heat Index)

When Does The Heat End?

- One more very hot day is ahead for most of the Eastern US, although few will near the century mark as we did on Tuesday.

- The Northeast will begin a temperature nosedive by Thursday, particularly in New England where temperatures will be in the 60s and 70s by week's end.

- For the mid-Atlantic, Ohio Valley and parts of the South, temperatures will be slower to come down, but they will come down. Instead of upper 90s, we'll be talking about lower to mid-90s by the end of the week. This may, unfortunately, come with a rise in humidity.

(MORE: Should You Turn Off Your A/C Or Leave It On When You Leave Home?)

Humid, Too

- Unlike temperatures, the tropical humidity is here to stay, with the exception of New England by the end of the week.

- Elsewhere the heat index, or feels-like temperature, will be in the 90s to low 100s from the East Coast into the South and parts of the Ohio and mid-Mississippi valleys through the week.

- This also means that overnight temperatures will not cool off or provide any relief from the daily heat.

(MORE: Why The Dew Point Temperature Matters)

What You Should Do

- Heat is the number one weather killer in the U.S., with hundreds of fatalities each year.

- The combination of heat and humidity lingering into the night for several days in a row could be dangerous for those without access to air conditioning, especially in the cores of larger cities.

- Check on family, friends, the elderly and those with chronic illness who live without access to air conditioning.

- If possible, avoid being outdoors for long in the peak heat of the afternoon.

- If not, take frequent breaks, avoid strenuous activity, drink more water than usual and wear loose, lightweight clothing.

(MORE: Heat Advice From An ER Doctor)

Why So Hot?

- A strong bubble of high pressure aloft known as a heat dome has persisted over the eastern U.S.

- Sinking air near the center of this heat dome suppresses clouds, allowing the intense sunshine this time of year to heat the ground and air above it most efficiently.

- This heat dome will only slowly weaken and "flatten out" in the East over the next few days.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.