Excessive and dangerous heat grips Plains, Midwest and Northeast

Heat index values could reach 115 degrees in parts of the Midwest.

Many of the major cities in the Midwest and Northeast -- from Chicago to Washington, D.C., and Philadelphia -- began a heat wave on Friday. New York City, which missed a 90-degree reading by just one degree, will likely hit the number Saturday to start a trend of its own.

Temperatures will soar well into the 90s across much of the Plains, Midwest and Northeast again today.

The heat index was 110 degrees and higher on Friday in parts of Illinois and Wisconsin. Pontiac, Illinois, hit a heat index of 115 degrees. Chicago's Midway International Airport hit a heat index of 110 degrees.

The heat will expand toward the Northeast on Saturday with temperatures in the 90s and heat index values into the upper 90s. The heat index in parts of the Midwest on Saturday could reach over 110 degrees, including in the Chicago metropolitan area.

Excessive heat warnings and watches have been issued for many major metropolitan areas, including Kansas City, Missouri; Chicago; Detroit; Philadelphia; New York City; Hartford, Connecticut; and Albany, New York. Heat advisories have been issued for much of the region from Oklahoma all the way to Vermont.

There will be little relief from the heat wave even at night. The actual temperature at 9 p.m. on Friday night in Chicago was 90 degrees, with a triple-digit heat index. Low temperatures in some of the major metro areas will struggle to dip below 80 degrees during their peak heat this weekend.

The actual temperature on Sunday will approach 100 degrees in New York City, Washington, D.C., Philadelphia and Hartford, Connecticut. Heat index values will soar into the 100s, with localized 105-degree heat-index values in urban areas of the Northeast.

The heat wave is currently forecast to last through July 4 -- at least. Furthermore, if the heat persists past the holiday, this heat wave could approach some of the notably long heat waves on record in locations like New York City and Albany, New York.

Severe weather hits Northern Plains

Another round of severe weather will fire up today across parts of the Midwest with damaging winds, large hail and brief tornadoes possible from Kansas to Michigan's Upper Peninsula. There is an enhanced risk for severe weather across parts of eastern Nebraska and Iowa where locally destructive winds and large hail could occur. The tornado threat is greatest in this region.

Cities that could see severe weather today include Des Moines, Iowa; Omaha, Nebraska; Kansas City, Missouri; and Minneapolis.

Additionally, storms will be move slowly due to the major ridge of high pressure bringing the heat wave to the east. Slow-moving thunderstorms will cause possible flash flooding. Locally, 2 to 3 inches of rain is expected in parts of eastern Nebraska and Iowa, with 3 to 4 inches or higher possible locally.

Fire threat continues

There are currently 56 large wildfires building across the western U.S. from New Mexico to Alaska.

The Spring fire in Costilla County, Colorado, has burned 28,648 acres and is 0 percent contained. There are mandatory evacuations in that area due to the fire.

The Waverly fire caused evacuations in Milton, California, on Friday. The fire has burned 10,000 acres and is only 10 percent contained.

It will be another day of warm temperatures across much of the West. Temperatures will be nearly 100 degrees in parts of interior California today.

Gusty winds, low relative humidity and high heat will bring the next round of high fire conditions across parts of Northern California and Utah.

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