KANSAS CITY, Missouri — Heavy to excessive rainfall on Wednesday, September 16, 2026 could bring areas of flooding across parts of the central Plains into the Midwest and Four Corners states, according to the weather outlook valid from 8:00 AM EDT Wednesday, September 16 through 8:00 AM EDT Thursday, September 17, 2026. The forecast map shows heavy rain and flash flooding possible across Arizona, New Mexico, Iowa, Illinois and Indiana, with a broad rain and thunderstorm zone covering an enormous footprint stretching from the Pacific Northwest through the Great Plains and into the Great Lakes region on Wednesday.
The red hatched pattern on the Wednesday, September 16, 2026 weather map identifies areas where heavy rain and flash flooding are considered possible. Two distinct hatched zones are shown:
- Arizona and New Mexico are covered by the largest heavy rain and flash flooding possible zone on the Wednesday, September 16 forecast map, consistent with the ongoing monsoon pattern bringing 2 to 3 inches of rainfall to the Four Corners region through September 17, 2026. Both states are fully covered by the red hatched heavy rain and flash flooding zone.
- Iowa, Illinois and Indiana are covered by a second distinct red hatched zone on the Wednesday, September 16 forecast map, identifying these three Midwest states as at risk for heavy rain and flash flooding during the same Wednesday timeframe. This is consistent with the ongoing excessive rainfall pattern that has been impacting the central Plains and Midwest through mid-September 2026.
The Broad Rain and Thunderstorm Coverage Wednesday
Beyond the heavy rain and flash flooding zones, the Wednesday, September 16, 2026 forecast map shows widespread rain and thunderstorm coverage across a massive area of the United States:
- Washington, Oregon, Idaho, Nevada and California all fall within the broader rain coverage zone on the Wednesday map, with multiple low pressure systems visible along the West Coast driving precipitation across the region.
- Montana, Wyoming, Colorado, Utah and Nevada are all within the rain and thunderstorm zone for Wednesday, September 16, 2026, consistent with the active weather pattern across the Intermountain West.
- North Dakota, South Dakota, Nebraska and Kansas fall within the rain and thunderstorm coverage zone on the Wednesday map, with a low pressure system visible over the central Plains driving moisture and storm development.
- Minnesota, Wisconsin, Michigan, Ohio, Pennsylvania, Indiana and Illinois all fall within the rain and thunderstorm zone for Wednesday, September 16, 2026, reflecting the broad and active weather pattern sweeping across the Great Lakes and Midwest.
- Missouri, Arkansas and Louisiana fall within the outer edges of the rain coverage zone on the Wednesday, September 16 forecast map.
- Virginia, West Virginia, Maryland, Delaware, New Jersey, Connecticut, Rhode Island, Massachusetts, New Hampshire, Vermont and Maine all fall within the rain zone on the eastern portion of the Wednesday, September 16 forecast map as a frontal boundary sweeps through the Northeast.
- Kentucky, Tennessee, North Carolina, South Carolina, Georgia and Florida fall within the broader rain coverage on the Wednesday, September 16 forecast map.
Tropical Disturbance Fifteen Also on the Map
The Wednesday, September 16, 2026 forecast map also identifies Tropical Disturbance Fifteen in the Atlantic south of Florida, visible at the bottom left of the map legend. This disturbance is being monitored as part of the active Atlantic weather pattern but is separate from the continental rainfall and flooding threat for Wednesday.
What Wednesday’s Setup Means for Residents
The combination of heavy rain and flash flooding possible across Arizona and New Mexico from the monsoon pattern and the separate heavy rain and flash flooding zone covering Iowa, Illinois and Indiana from the central Plains storm system means two distinct regions of the country face serious flooding concerns on the same day. Residents in Phoenix, Albuquerque, Santa Fe, Des Moines, Cedar Rapids, Chicago and Indianapolis should all monitor local flash flood watches and warnings closely through 8:00 AM EDT Thursday, September 17, 2026.
