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By Amanda Greenwood and Joe Edwards
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The North American monsoon could bring welcome rain to parts of the drought-hit Southwest this summer but forecasters and water specialists warn it is unlikely to meaningfully reverse the crisis gripping Lake Powell and Lake Mead.
The two reservoirs—the largest in the United States and critical storage points for the Colorado River—remain at severely depleted levels after years of drought, climate change-driven aridification and heavy demand from cities, farms and tribal communities across the West.
As of July 19, Lake Powell stood at 3,523.43 feet, holding 5.455 million acre-feet of water, or 23 percent full, while Lake Mead was at 1,041.81 feet, holding 7.103 million acre-feet, or 27 percent full, according to the Bureau of Reclamation’s latest hydrologic update. The total Colorado River system storage was 33 percent of capacity, down from 39 percent a year earlier.
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What To Know
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The North American monsoon is a seasonal shift in wind patterns that draws moisture northward from Mexico, the Gulf of California and the eastern Pacific into the Southwest. It typically brings thunderstorms, heavy downpours, lightning and flash-flood risk to parts of Arizona, New Mexico, Utah, Colorado and surrounding states.
The National Integrated Drought Information System (NIDIS) said the official monsoon season runs from June 15 to September 30, although the actual arrival varies by year.
The 2026 monsoon outlook points to an active season in parts of the region. NIDIS said seasonal forecasts were "leaning toward above-average overall precipitation this summer," bringing potential short-term drought relief across the Southwest.
The National Weather Service (NWS) July 16 outlook for New Mexico said there was "moderate confidence" for near-normal precipitation in central and eastern New Mexico and "moderate to high confidence" for above-normal precipitation in western New Mexico from July through September.
The National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center also favored above-normal precipitation from the Southwest into parts of the Northern Rockies and Central Plains for August through October, with the strongest odds—40 to 50 percent—over parts of Southern California, Nevada, Utah and western Arizona.
But the monsoon’s impact on Lakes Powell and Mead is expected to be limited.
NIDIS said plainly: "The monsoon will likely have little influence on streamflow in the Colorado and Rio Grande Rivers" and "reservoir levels across the region will likely not see substantial change from monsoon season rainfall."
That’s because Lake Powell is mainly filled by Rocky Mountain snowmelt, not summer thunderstorms.
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Paul Miller, Service Coordination Hydrologist at NOAA's Colorado Basin River Forecast Center, told Newsweek that the Colorado River system is driven overwhelmingly by mountain snowpack rather than summer rainfall.
"The vast majority—85 to 95 percent—of water that feeds the Colorado River Basin comes from mountain snowpack," Miller said. "Summer monsoonal precipitation can provide some benefit, like allowing agriculture to utilize local rainfall instead of relying on deliveries from the Colorado River system, and that can provide some benefit to the basin, but it's relatively minimal and short-term in nature."
Miller added that monsoonal storms tend to provide the greatest benefits to the desert Southwest, where localized rainfall can temporarily ease drought conditions.
The Bureau of Reclamation said precipitation in the Upper Basin during water year 2026 (which runs from October 1, 2025, through September 30, 2026) has been well below average, reaching just 78 percent of normal levels. As a result, Lake Powell is expected to receive far less water than normal, with inflows forecast at just 36 percent of the average for the year. The important April-to-July snowmelt runoff period is projected to be especially poor, at only 17 percent of normal.
Water specialists say the combined condition of Lakes Powell and Mead is especially alarming. In a July 14 research paper, Colorado River experts Jack Schmidt, Anne Castle, John Fleck, Eric Kuhn, Kathryn Sorensen and Katherine Tara, said the two reservoirs held a combined 12,675,509 acre-feet of live storage on July 12—the lowest combined total since May 1957, before Lake Powell began filling.
Schmidt, who directs the Center for Colorado River Studies at Utah State University, told radio station KJZZ the milestone was "a significant moment" in the river’s supply crisis.
"It’s a real reminder of what a remarkably small amount of water we have left in the system," Schmidt said. "We’ve never been in this position. We are truly in uncharted territory."
The same group of experts wrote that Powell and Mead should be viewed as "one gigantic reservoir, separated into two parts by the Grand Canyon," because together they store water downstream of major Upper Basin uses and upstream of major Lower Basin uses. Their paper said combined storage had been declining by roughly 16,000 af per day since March—the only exception was May, when losses slowed to around 11,000 acre-feet per day—and warned that every day before next spring’s snowmelt could set another record low.
Why the Monsoon May Not Move the Needle
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Monsoon storms can help soils, vegetation and short-term drought conditions, especially in Arizona and New Mexico, where parts of the region depend on summer rainfall. NIDIS noted that parts of Arizona and New Mexico typically receive 50 to 75 percent of their annual rainfall during the monsoon season.
However, summer thunderstorms are often highly localized and intense, meaning some areas can see flooding while nearby watersheds remain dry. The National Weather Service (NWS) warned that seasonal outlooks do not predict specific daily weather and that "sub-seasonal variability" can produce both dry and wet periods. It added: "All it takes is one extreme rainfall event to produce destructive, life-threatening flooding impacts."
The best-case scenario for the reservoirs would likely be indirect: Monsoon rain could reduce irrigation demand, ease wildfire risk in some areas, improve soil moisture and provide modest inflows from tributaries if storms repeatedly hit the right watersheds. But it would not replace the large-scale spring runoff that normally comes from mountain snowpack.
What Happens Next
The Bureau of Reclamation’s outlook shows both reservoirs are expected to continue declining through the end of 2026. The agency projected Lake Powell at around 3,508 feet and Lake Mead at around 1,037 feet by the end of the calendar year.
The broader question isn’t whether one wet monsoon can rescue the system, but whether Colorado River users can reduce demand enough to match a shrinking supply.
Miller told Newsweek that: "The Colorado River system as a whole is at only about 33 percent capacity. To fill it, we would need at least five to six years of average inflow and zero water use."
According to the Bureau of Reclamation, the current operating rules for Lake Powell and Lake Mead expire at the end of 2026, but it’s working on post-2026 guidelines that will shape how shortages and reservoir operations are managed for years to come.
For now, the American monsoon may bring bursts of rain and some local drought relief. But for Lake Mead and Lake Powell, forecasters and water experts suggest the crisis will remain driven by the same larger forces: Poor snowpack, reduced runoff, long-term aridity and continued pressure on the Colorado River.
Newsweek has contacted the River Operations group at the Bureau of Reclamation by email for comment.
Contact Newsweek editors on this story: Ben Kelly and Tony Phillips
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