Heat will build across the region this weekend, with the heat index exceeding 100 degrees in many areas today through Monday in south central Iowa. A heat advisory has been issued for most of the area. Overnight lows in the 70s will provide little relief over the next three days. Those with outdoor plans should take precautions, including staying hydrated and taking frequent breaks in shade and air conditioning. A cold front will likely sweep through the area by Tuesday afternoon, according to the National Weather Service.