TonightClear, with a low around 79. South southwest wind around 15 mph, with gusts as high as 25 mph. SundaySunny and hot, with a high near 95. Heat index values as high as 104. Southwest wind around 15 mph, with gusts as high as 30 mph. Sunday NightClear, with a low around 78. South southwest wind 10 to 15 mph, with gusts as high as 25 mph. MondaySunny and hot, with a high near 96. Heat index values as high as 100. Southwest wind 10 to 15 mph, with gusts as high as 25 mph. Monday NightA 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 73. Southwest wind 5 to 10 mph, with gusts as high as 20 mph. TuesdayA 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 81.Tuesday NightA 40 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 67.WednesdayShowers and thunderstorms likely, mainly after 1pm. Partly sunny, with a high near 78.Wednesday NightA chance of showers and thunderstorms. Mostly cloudy, with a low around 68.ThursdayShowers and thunderstorms likely, mainly after 1pm. Mostly sunny, with a high near 88.Thursday NightA chance of showers and thunderstorms. Partly cloudy, with a low around 68.FridayA chance of showers and thunderstorms. Partly sunny, with a high near 85.Friday NightA chance of showers and thunderstorms. Mostly cloudy, with a low around 67.SaturdayA chance of showers and thunderstorms. Mostly sunny, with a high near 85. , NOAA National Weather Service. A chance of showers and thunderstorms before 7am, then a chance of showers between 7am and 1pm, then a chance of showers and thunderstorms after 1pm., Be prepared with the most accurate 10-day forecast for Lake Forest, IL with highs, lows, chance of precipitation from The Weather Channel and Weather.com.