A passing wave of low pressure and trailing cold front are driving elevated rain chances across the Northeast US on September 13, 2026, with widespread showers and embedded thunderstorms expected overnight into the morning hours before gradual clearing. National Weather Service forecasts indicate a high probability of measurable precipitation in the New York and Albany regions, supported by southerly moisture transport and dew points rising into the upper 60s, though totals may vary with localized heavy bands. In contrast, Florida faces scattered afternoon storms at 40-50% odds, while California and parts of the Southeast remain mostly dry under high pressure. Traders should watch real-time NWS radar, satellite observations, and updated model runs for confirmation of precipitation thresholds in specific cities, as steering patterns and timing can shift outcomes quickly on the day of resolution.