Overview
- The National Weather Service and multiple forecasters warned Wednesday that a large heat dome will strengthen and peak Thursday–Friday and continue into the July 4 weekend across a corridor from the Plains to the East Coast.
- Forecasts project air temperatures commonly in the mid‑90s to low‑100s and heat‑index values of about 100–115°F, with unusually warm nights in the 70s–80s that limit overnight cooling and raise cumulative heat stress.
- Cities and counties have opened cooling centers, deployed mobile cooling vans and adjusted event plans while utilities have urged reduced energy use and dimmed nonessential lighting to reduce the risk of local grid strain.
- Medical and emergency teams are preparing for more heat‑related visits, with doctors warning that heat exhaustion can quickly progress to life‑threatening heat stroke for older adults, children, outdoor workers and people without reliable air conditioning.
- Meteorologists link the event to a persistent upper‑level high‑pressure ‘heat dome’ and say large‑scale drivers such as a strong El Niño plus long‑term warming are increasing the intensity and duration of the heat.