The persistent rain and thunderstorms are expected to exacerbate flooding issues in Chicago, which has already experienced 'unprecedented flooding' this summer, according to Mayor Brandon Johnson. The heavy rainfall could lead to waterlogged streets, sewer overflows, and potential property damage. Residents in flood-prone areas should remain vigilant, as the storms may bring localized flooding and hazardous driving conditions. The city has already faced significant challenges, including power outages and infrastructure damage, due to previous storms this summer.