ALBUQUERQUE, New Mexico — An increasing risk of localized flooding is developing across the Four Corners and Desert Southwest through Wednesday, September 17, 2026, as robust monsoonal moisture wafting northward fuels scattered to numerous downpours across the region. A few of these storms will train, meaning they move repeatedly over the same areas, stacking rainfall totals and dramatically increasing the flash flooding risk for communities from Cortez and Albuquerque down through Phoenix, Silver City and Las Cruces. The heaviest rainfall zone of 2 to 3 inches is centered over the Four Corners area, with widespread 1 to 1.5 inch totals extending across a much broader footprint through September 17.
Rainfall Totals by Zone Through September 17
The forecast maps show three distinct rainfall zones across the Four Corners and Desert Southwest through Wednesday, September 17, 2026:
- The 2 to 3 inch zone, shown in bright pink on both forecast maps, is centered over the Four Corners area near Cortez and extending southeast through Albuquerque and Santa Fe, New Mexico. This is the highest rainfall total zone on the map and carries the greatest localized flooding risk through September 17.
- The 1 to 1.5 inch zone covers two separate areas — one centered over Grand Junction, Price and Moab in the northern portion of the forecast area, and a second covering Phoenix, Silver City and Las Cruces in the southern portion. Both zones face meaningful rainfall accumulation and localized flooding potential through September 17.
- The less than 1 inch zone covers the outer edges of the forecast area including Fort Collins and the Denver corridor to the northeast and the Flagstaff and Las Vegas area to the west, where lighter but still significant monsoon rainfall is expected through September 17.
Cities Facing the Heaviest 2 to 3 Inch Rainfall Zone
The following cities are visible within or near the 2 to 3 inch rainfall bull’s-eye through September 17, 2026:
- Cortez sits directly within the 2 to 3 inch rainfall zone on both forecast maps through September 17, 2026, placing it at the highest localized flooding risk in the entire forecast area.
- Albuquerque, New Mexico falls within the 2 to 3 inch zone through September 17 and is one of the largest cities facing the most intense monsoon rainfall in this event.
- Santa Fe, New Mexico is visible within the 2 to 3 inch rainfall zone on both forecast maps through September 17, 2026.
- Gallup, New Mexico falls within or near the 2 to 3 inch zone on the forecast maps through September 17.
- Alamosa is visible within the 2 to 3 inch zone on the forecast maps, sitting at the northern edge of the heaviest rainfall footprint through September 17, 2026.
Cities in the 1 to 1.5 Inch Rainfall Zone
The 1 to 1.5 inch rainfall zone covers a broad area both north and south of the 2 to 3 inch bull’s-eye through September 17, 2026:
- Grand Junction sits within the northern 1 to 1.5 inch zone through September 17, with the rainfall label centered directly over this area on both forecast maps.
- Price, Vernal and Moab are visible within or near the northern 1 to 1.5 inch rainfall zone through September 17, 2026.
- Phoenix falls within the southern 1 to 1.5 inch zone through September 17, with the rainfall label positioned directly over the Phoenix area on the forecast maps.
- Silver City and Las Cruces, New Mexico are visible within the southern 1 to 1.5 inch rainfall zone through September 17, 2026.
- Nogales is visible at the southern edge of the 1 to 1.5 inch zone on the forecast maps through September 17.
- Richfield and St. George are visible within the broader rainfall footprint on the western edge of the forecast area through September 17, 2026.
Cities in the Less Than 1 Inch Zone
The outer edges of the monsoon rainfall footprint show less than 1 inch of expected rainfall through September 17, 2026 for the following cities:
- Fort Collins and Denver are visible at the northeastern edge of the rainfall footprint, sitting within the less than 1 inch zone through September 17.
- Flagstaff is visible within the less than 1 inch zone on the western edge of the forecast area through September 17, 2026.
- Las Vegas and Kingman are visible on the western edge of the forecast maps within the lighter rainfall zone through September 17.
- Pueblo, Salida and Lamar are visible on the eastern edge of the rainfall footprint through September 17, 2026.
- Roswell and Carlsbad, New Mexico are visible on the southeastern edge of the forecast maps within the broader but lighter rainfall zone through September 17.
- Cheyenne is visible at the very northern edge of the forecast area within the outer rainfall zone through September 17, 2026.
What Monsoon Training Storms Mean for Flash Flooding
The source data specifically warns that a few of today’s downpours will train, meaning they move repeatedly over the same locations rather than passing through quickly. When storms train over a single area, each new cell drops additional rainfall on ground that is already saturated from the previous cell, causing water to accumulate rapidly on roads, in washes, arroyos and low-lying areas. Even 1 to 2 inches of rainfall from a training storm event can cause life-threatening flash flooding in desert terrain, where hardpan soils and rocky ground cannot absorb water and runoff channels rapidly fill and overflow. The 2 to 3 inch totals forecast near Cortez and Albuquerque from training storms represent a serious and potentially dangerous flash flooding scenario through September 17, 2026.
Flash Flood Safety in the Desert Southwest
Flash floods in the Desert Southwest and Four Corners are among the most dangerous in the country because they can arrive with little warning, even in areas where no rain is falling locally. Water from storms miles away can funnel into canyons and washes and create walls of water that move faster than a person can run. Never cross a flooded wash or road, never camp in a canyon or arroyo during monsoon season and always monitor radar for storms upstream from your location through Wednesday, September 17, 2026.
