The heat is on in the Midwest, and humidity is joining in to make the heatwave misery the worst it's been in five years in the region.

Forecasts say also the dangerous mix of heat and humidity stifling the Midwest will spread east by mid-week, taking a toll for a few days in New York City and throughout the East Coast region.

In the Midwest Monday, excessive heat warnings were posted throughout America's midsection, with heat indexes from the high temperature and high humidity combination rising to 115 or above forecast for Illinois, Wisconsin, Minnesota, Iowa, Missouri, Kansas, Nebraska, Oklahoma and South Dakota and North Dakota.

This will likely be the most significant heat wave the region has experienced in at least the last five years, the National Weather Service said in a statement.

The heat wave will grip at least 40 of America's 50 states by mid-week, meaning temperatures will climb above 90 degrees Fahrenheit or higher and humidity levels will rise as well, creating the potentially deadly high heat indexes that rise above 110. Officials have urged citizens in many areas to stay out of the heat in the intense portions of the day, if possible.

Records are expected to fall in cities across America setting new high temperatures, including Springfield, Illinois, Rapid City, South Dakota, and Minneapolis, Minnesota. Many cities throughout the heat-baked region will see temperatures at 100 degrees or more for the entire week, forecasters say.

In Chicago, an alert for poor air quality was in place as temperatures were expected to reach 95 degrees by mid-afternoon Monday, with heat indexes climbing above 105 due to high humidity. While in St. Louis, a high temperature of 96 on Sunday is expected to be eclipsed on Monday with a high at or near 100 degrees with a heat index of 110 to 115.

America's largest city and others along the East Coast won't be spared the heatwave, either.

New Yorkers are starting the week off with temperatures forecast to rise above 90 mixing with potentially severe thunderstorms by Wednesday night time lows are predicted to drop to only 78 degrees. The high temperature forecast for New York Friday is 95 degrees, with a low of 76, before temperatures are expected to cool off to more seasonal levels early the next week.

America's capital won't be spared, either, as forecasters say temperatures in Washington, D.C. will approach or exceed 100 degrees by mid-week.