On September 13, 2026, National Weather Service and NOAA guidance indicate the primary rain focus across the Northeast and parts of the Mid-Atlantic, where a lingering frontal system and associated moisture are producing widespread showers and thunderstorms with probabilities often exceeding 70-90 percent in locations such as Boston, New York, and coastal New Jersey. Model consensus supports scattered to numerous showers tapering from west to east through the afternoon, while the Southeast, Gulf Coast, and much of the interior South remain mostly dry under high pressure with only isolated storm chances around 20-50 percent. Official surface observations and radar data will determine measurable precipitation at specific stations for market resolution, with any late-day clearing or redevelopment tied to frontal passage.