A dangerous heat wave will hold across the eastern two-thirds of the country through the Fourth of July weekend, pushing heat indices to between 100 and 115 degrees from the Midwest to the Northeast, forecasters said.
Behind the heat is a strong upper-level ridge parked over the central and eastern United States through the weekend, holding it in place, according to the National Weather Service's Weather Prediction Center. Highs will run from the mid-90s into the low 100s, and with dewpoints in the 70s, the heat index, the measure of how hot it actually feels, will peak between 100 and 115 degrees. Numerous daily temperature records are possible.
Overnight lows will stay in the 70s and 80s, so the heat does not let up after dark. The weather service has flagged Major to Extreme HeatRisk, the top two levels of its scale for how dangerous heat is to human health, across the Midwest and into the East Coast, with Extreme Heat Warnings and Heat Advisories posted across the Mississippi Valley, Great Lakes, Ohio Valley, and Northeast through Friday.
The West is the exception. A trough over the western United States is keeping much of that region cooler than normal, which leaves the coolest holiday-weekend weather over the interior West and its high country.
For anyone heading out for the long weekend, the forecast redraws the map. The heat covers most of the popular eastern and midwestern destinations just as the holiday begins, the comfortable air sits out West, and the seam between them across the northern tier trades heat for severe storms and flash flooding.
That seam is its own hazard. A stalled front from the northern Plains into the Upper Midwest and Great Lakes will touch off rounds of thunderstorms capable of damaging winds, large hail, and heavy rain, and forecasters have posted a risk of flash flooding there Thursday into Friday. The severe-storm threat expands into the Mid-Atlantic on Friday. Farther west, critical fire-weather conditions continue over parts of the Four Corners through Friday.
The heat built in the Midwest around Monday and spread east, and it now covers more than two dozen states, according to ABC News.
What to check before you head out
- Look up your destination on the HeatRisk map. The weather service grades every location green through magenta by how dangerous the heat is that day; Major and Extreme are the two highest levels, and they cover much of the eastern half of the country this weekend.
- Plan around the heat of the day. The danger peaks from midday into the evening. Warm overnight lows mean a vehicle without air conditioning gives no real recovery at night, so sleeping in a hot rig or tent is harder than it looks on paper.
- Carry more water than usual, for people and dogs. Never leave either in a parked vehicle, and check pavement and sand with a hand before a dog walks on it.
- The West and the high country are the refuge. If plans are flexible, that is where the comfortable, record-free weather is this weekend.
- Heading to the northern tier or the Four Corners? Watch for severe storms and flash flooding across the northern Plains and Great Lakes, and check fire restrictions before any Four Corners trip.
Quick answers
Where is the July 4 heat wave worst?
The Midwest, Ohio Valley, Mid-Atlantic, and Northeast, where heat indices will reach 100 to 115 degrees and the weather service has posted Extreme Heat Warnings and Heat Advisories through Friday.
Where is it cooler this weekend?
Much of the western United States, where a trough is holding temperatures below normal, including the interior West and its high country.
Does the heat let up at night?
Not much. Overnight lows in the 70s and 80s leave little recovery, which is part of what makes this event dangerous.
The coolest, calmest weather in the country this holiday weekend sits over the western high country, while most of the East rides out the heat.
How we reported this
- NOAA / NWS Weather Prediction Center, Short Range Forecast Discussion, issued 150 AM EDT July 2, 2026, valid through July 4. wpc.ncep.noaa.gov. The authoritative federal forecast for the heat, the storm threat, and the fire-weather risk.
- NWS HeatRisk, wpc.ncep.noaa.gov/heatrisk. The color-coded, location-level heat-danger tool referenced in the service section.
- ABC News, "Heat wave forecast: Dangerous temps to continue into July 4 holiday," July 2, 2026. abcnews.com. Corroborating coverage on the wave's timing and reach.