(The Hill) — The National Weather Service (NWS) is warning of “persistent, dangerous heat” for much of the week, especially in the southern and southwestern parts of the country.

The “early July heat wave” is expected in the Southern Plains, Gulf Coast, Southeast and Mid-Atlantic Coast, Central Valley of California and Mojave Desert of California and Nevada, the NWS said Monday.

The NWS is warning specifically of “significant heat” on the July Fourth holiday.

“Independence Day activities may be impacted by dangerous heat,” the NWS said. “Use caution and check the forecast. Stay hydrated, and limit time outdoors in the heat.”

California’s Central Valley and the Mojave Desert should expect “many days of record high and low temperatures” continuing throughout the week, with highs topping 110 degrees.

The western heat wave will continue into next week, expanding northward into the Pacific Northwest and Intermountain West, NWS said.

In the South and Southeast — especially along the coast stretching from eastern Texas into much of Florida — the NWS is warning of heat index values approaching or exceeding 110 degrees. The danger of the heat results from the high temperatures as well as the high humidity in these regions, NWS said.

Overall, the prolonged nature of the continued heat “will increase the risk of heat-related illness,” the NWS warned.

“Sizzling heat will be the top story leading up to Independence Day across the South Central U.S.,” the NWS Weather Prediction Center said, also warning of “stormy weather” in parts of the Midwest, Ohio Valley and Southeast.