Illinois is bracing for a volatile week of weather, starting with thunderstorms and transitioning into a significant heat wave. Residents should prepare for both severe weather risks and extreme heat conditions.

A round of thunderstorms is expected to sweep through Illinois today, bringing the risk of heavy rainfall and isolated severe weather. The National Weather Service in Chicago has issued a 70% chance of storms through Saturday afternoon, with the most significant risk for areas south of Interstate 80. Localized flooding is possible, so residents are advised to stay informed and avoid low-lying areas.

Lake Michigan also presents hazards today, with a high swim risk and the potential for dangerous rip currents. Swimmers should exercise extreme caution and heed all warnings from local authorities.

The stormy pattern will persist into Sunday and Monday, with scattered and intermittent showers mainly affecting southern regions near Peoria and Kankakee. While temperatures will remain relatively mild, hovering in the upper 70s to low 80s, this offers only a brief respite before the arrival of a major heat wave.

Starting Tuesday, temperatures will begin to climb rapidly across the state. Wednesday and Thursday are forecast to be the hottest days of the week, with potentially dangerous conditions.

Heat indices are expected to soar between 105°F and 115°F across the Chicago metro area, Rockford, and much of northern Illinois. Such extreme heat poses serious health risks, especially for vulnerable populations like the elderly, children, and those with pre-existing medical conditions. It can also strain infrastructure, potentially leading to power outages and other disruptions.

Residents are strongly advised to take the following precautions: * Stay indoors during the hottest parts of the day (typically between 10 AM and 4 PM). * Seek air-conditioned environments whenever possible, such as shopping malls, libraries, or community centers. * Stay well-hydrated by drinking plenty of water, even if you don't feel thirsty. * Avoid strenuous activities during peak heat hours. * Wear lightweight, light-colored clothing. * Check on elderly neighbors, friends, and relatives who may be more susceptible to heat-related illnesses.

Authorities anticipate increased strain on the power grid due to high demand for air conditioning. Residents should conserve energy where possible to help prevent outages. Report any power outages to your local utility company immediately.

Excessive Heat Watches are expected to be issued starting Monday, signaling the imminent arrival of dangerous heat conditions. The National Weather Service will provide daily updates throughout the heat wave, so stay tuned to local news and weather reports.

* **Saturday:** Thunderstorms likely (70%), humid; Highs 82–86°F / Lows 65–70°F * **Sunday:** Scattered storms, high swim risk; Highs 74–82°F / Lows 60–70°F * **Monday:** Spotty storms; Highs 78–83°F / Lows 64–70°F * **Tuesday:** Mostly sunny, hotter, humid; Highs 84–89°F / Lows 70–75°F * **Wednesday:** Dangerously hot; Highs 92–95°F (Heat Index 105–115°F) / Lows 72–77°F * **Thursday:** Continued extreme heat; Highs 90–94°F / Lows 69–73°F

Prepare now for both thunderstorms and a potentially deadly heat wave. Stay informed, stay safe, and take care of yourself and your neighbors.