Monsoon moisture has started arriving across Southern California with higher humidity and thunderhead clouds popping up over the mountain and desert microclimates. We will see slightly cooler afternoon highs with the clouds, but the slightly cooler temperatures are being replaced with sticky conditions. The peak of monsoonal flow will be on Monday, with a 50% chance of thunderstorms in the afternoon over the mountains and deserts; rainfall totals could range from .25" - .50". MORE: https://www.cbs8.com/weather/