Arizona's Monsoon Forecast: What to Expect This Tuesday.

Here is your Monsoon Outlook for Tuesday, July 21, 2026, provided by the US National Weather Service Flagstaff, Arizona . Graphic from U.S. National Weather Service Flagstaff, Arizona. Monsoon According to the US National Weather Service, Flagstaff, Arizona , A Flash Flood Watch remains in effect this afternoon and evening, and has been expanded to include all of Yavapai County. Increased potential for thunderstorms with heavy rain that could lead to flash flooding. Avoid flood-prone areas like