(NewsNation) — An intense heat wave continues to impact 160 million people in the North, as temperatures will near the 100-degree mark.

Excessive heat warnings and heat advisories were issued Sunday for 85 million Americans in regions with temperatures hitting 105 degrees or higher, according to the National Weather Service. This heat can be very dangerous, so it is important to stay hydrated and limit time outdoors if possible.

A potent cold front will extend from New York to Illinois Sunday, producing strong thunderstorms. The main threats will be flooding downpours, damaging wind gusts and hail. An isolated tornado cannot be ruled out.

It will be dangerously hot ahead of the cold front with temperatures feeling like they’re 90-105 degrees during the peak of the afternoon heat.

Strong thunderstorms with damaging winds will impact a swath from Montana to western Nebraska.

Also, the NWS reported that severe weather and flash flood threats are expected to stretch from the Middle Mississippi Valley to the Mid-Atlantic Coast Monday.

Monsoonal storms will impact the Southwest and Southern Rockies through Monday, bringing daily rounds of excessive rainfall and isolated flash flooding, according to the NWS.

The heat wave will continue this week in the Northwest, with temperatures 8-17 degrees above normal for this time of the year. Temperatures are expected to reach between 92-110 degrees in Washington state and parts of Oregon.

The NWS on Sunday issued an excessive heat watch for the U.S. Pacific Northwest region for coming days as potential record-breaking temperatures were forecast to settle in and linger until next weekend.

Temperatures could break daily records in Seattle, Portland and areas of Northern California by Tuesday, potentially reaching their highest levels since last year’s deadly heat wave that killed hundreds of people across the Pacific Northwest.

Highs ranging from 95 degrees to 110 degrees were forecast for inland areas. An excessive heat watch was issued for central and eastern Washington state and the central Idaho Panhandle from Tuesday morning through Friday evening.

Much of the region is unaccustomed to such high temperatures and many homes don’t have air conditioning. Authorities cautioned that indoor heat was likely to build through the week, increasing the chances for people to suffer heat-related illnesses.

The Associated Press contributed to this report.