A high-pressure heat dome system positioned over the eastern United States has led to record-breaking heat conditions across the Northeast and parts of the Mid-Atlantic beginning June 23, 2025.
The National Weather Service (NWS) has issued heat advisories and excessive heat warnings for multiple states as roughly 245 million people experienced temperatures at or above 32°C (90°F), and about 33 million faced temperatures at or above 38°C (100°F).
Forecast data and observations confirm that temperatures exceeded 38°C (100°F) in major urban centers, including New York City and Philadelphia, on Monday, June 23. In New York City, Central Park reached 36°C (96°F), tying a record set in 1888.
New York City also saw unusually warm overnight conditions, with temperatures falling no lower than 27°C (81°F). This marks the earliest occurrence of a nighttime low at or above 27°C (80°F) in the recorded history of the city. Philadelphia also reported a high of 37°C (99°F), marking its hottest day since July 2022.
Salt Lake City, Utah, recorded its first triple-digit temperature of 2025 as it reached 40°C (104°F) on June 20, while Mitchell, South Dakota, recorded 40°C (104°F) on June 22, surpassing its previous daily record of 38.3°C (101°F). Daily maximum temperature records were also broken in parts of Minnesota, Wyoming, and Michigan.
NWS offices have issued extreme heat warnings and advisories from Missouri to Maine that are stretching southeast up to Florida. This covers millions of people across more than 28 states.
According to the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center (CPC), this event is part of a broader seasonal trend of above-average temperatures across the continental United States.
The heat dome is expected to weaken later this week, with relief arriving by Thursday in New England and the Upper Midwest. The Mid‑Atlantic and Southeast are forecasted to remain above normal into early July.
Authorities are warning of increased health risks such as heat exhaustion, heatstroke, and dehydration. They advise staying well-hydrated, avoiding outdoor activity during peak heat hours, and checking on vulnerable individuals such as the elderly and those with underlying health conditions.
