**Scattered thunderstorms driven by monsoonal moisture and weak frontal boundaries are the main factors shaping probabilities for measurable rain on August 29, 2026.** National Weather Service and WPC guidance highlight a slight risk of excessive rainfall along the coastal Carolinas into southern Georgia, with 12-hour precipitation probabilities often exceeding 50% in parts of the Southeast and Florida due to high precipitable water values and daytime heating. Southwest monsoonal flow supports isolated to scattered storms across Arizona, New Mexico, and the Rockies, while northern and interior western areas remain drier under stronger ridging. Short-term radar trends and afternoon model updates from NOAA will refine localized chances, particularly where convection organizes near stalled boundaries or terrain. These patterns align with typical late-August climatology of diurnally driven showers rather than widespread organized systems.