Residents in Miami should brace themselves for a mixed bag of weather conditions as both warmth and potential storms are on the horizon. According to the National Weather Service, folks should expect “a 20 percent chance of showers and thunderstorms, mainly between 11am and 1pm.” But despite the chance of rain, the day remains mostly sunny, with a high creeping up near 90 degrees and heat index values threatening to soar as high as 103.