A dangerous stretch of heat is expected to continue through Friday, with forecasters warning that heat and humidity could affect nearly 250 million people during the Independence Day holiday week.
AccuWeather meteorologist Brandon Buckingham said the combination of high temperatures and oppressive humidity will create hazardous conditions, especially during the afternoon and evening hours.
Buckingham said while summer heat waves are common, the current weather pattern has been intensified by a strong heat dome that strengthened after cooler air moved into the western United States.
“It’s summer. We expect some heat,” Buckingham said. “But when you factor in the humidity, that’s what’s driving those dangerous feel-like temperatures.”
The National Weather Service has issued an Extreme Heat Warning for parts of New York and Pennsylvania through Friday evening. Heat index values are expected to climb into the triple digits in many locations, while overnight temperatures will remain unusually warm, offering little relief.
Buckingham said the persistent humidity can make it harder for the body to cool itself.
“When you factor in the humidity, it causes your body to sweat more, making it harder to stay hydrated than it would be in a dry heat,” he said.
Higher Elevations Offer Limited Relief
While mountain communities in the Catskills may be slightly cooler than valley locations, Buckingham said residents should not expect to escape the heat entirely.
Afternoon temperatures at higher elevations are expected to reach the mid- to upper 80s, while many valley communities could see highs in the low to mid-90s.
Outdoor Holiday Events Face Heat, Storm Risks
The heat arrives as millions of Americans prepare for Fourth of July celebrations, including parades, cookouts, fireworks and festivals.
Buckingham advised limiting strenuous outdoor activity between about noon and 6 or 7 p.m., when temperatures and humidity will be at their highest.
He also warned that the weather threat will expand beyond the heat as the weekend progresses.
Scattered thunderstorms are expected Friday through Sunday as the heat dome begins to weaken. Some storms could produce damaging wind gusts, heavy rainfall and localized flooding.
People attending outdoor events or spending time camping or hiking should have a reliable way to receive weather warnings, especially in areas with limited cell phone service, Buckingham said.
Most Vulnerable Populations
Buckingham said young children and older adults remain the most vulnerable during periods of extreme heat, particularly those without access to air conditioning.
For people without air conditioning, he recommended spending time in cooling centers or other air-conditioned public buildings, or seeking relief at pools, lakes or other safe swimming areas during the hottest part of the day.
Looking Ahead
While temperatures are expected to ease somewhat beginning Saturday, Buckingham said humidity will remain high through the holiday weekend and into early next week.
High temperatures are forecast to fall into the mid-80s by Sunday and Monday, but daily chances for showers and thunderstorms are expected to continue.
Looking further ahead into July, Buckingham said the overall weather pattern favors continued humid conditions with periodic rounds of showers and thunderstorms through at least the middle of the month.
Image: Jessica Weiman drags out a hose on a hot day while watering flowers Wednesday, July 1, 2026, in Cincinnati. (AP Photo/Joshua A. Bickel)
Tips for staying safe in the heat
- Drinking plenty of fluids, seeking shade or air-conditioning and staying out of the sun can help protect you from heat.
- If you have to be outside, wear light and loose-fitting clothing and limit strenuous activities during the hottest times of the day.
- Use cooling fans or towels and drink slushies or other icy beverages.
- Limit the amount of alcohol you drink and hydrate before it gets really hot.