As the summer's first heat wave continues, the chance for rain and somewhat cooler temperatures wait in the wings for northeast Missouri and western Illinois.

The National Weather Service's heat advisory for the area continues through 8 p.m. Tuesday. High temperatures in the mid 90s and high humidity levels will combine for heat index values as high as 105 Monday and Tuesday.

Temperatures start to drop off Wednesday, sliding from 89 Wednesday to 82 by Sunday. Overnight lows for the week start in the low 70s, dropping to the mid 60s by the weekend.

Varying chances of showers and thunderstorms are in the forecast Wednesday through Sunday, with percentages ranging from 20 to 40 percent.