The National Weather Service has issued an extreme heat watch for portions of northern and central Illinois from Wednesday morning through Thursday evening.

Forecasters say that dangerously hot conditions could occur with heat index values of 105-115 degrees.

The watch covers Cook, DeKalb, DuPage, Kendall, Lake, McHenry, McLean, Peoria, Tazewell, Winnebago and Woodford counties.

Madison and St. Clair counties are under an extreme heat warning from now until 7 p.m. Thursday, with heat index values up to 110 degrees expected.

Medical experts note that heat-related illnesses increase significantly during extreme heat and high-humidity events.

Residents are encouraged to:

• Drink plenty of fluids.
• Stay in an air-conditioned room.
• Stay out of the sun.
• Check on relatives and neighbors.
• Take extra precautions if you work or spend time outside.
• When possible, reschedule strenuous activities to early morning or evening.
• Know the signs of heat exhaustion and heat stroke.
• Wear lightweight and loose fitting clothing, when possible.
• To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air-conditioned environments.
• Anyone overcome by heat should be moved to a cool and shaded location.

Residents in the St. Louis metropolitan area can get information about cooling centers or energy assistance related to the excessive heat by calling United Way of Greater St. Louis at 1-800-427-4626 or if calling from a landline telephone, dial 211. Residents can also call Cool Down St. Louis at 314-241-7668.