The western United States is facing the harsh impacts of climate change, with record-low snowfall and an early heatwave significantly reducing snowpack, a crucial water source for many states during summer. This climate shift, driven by fossil fuel emissions, is altering the winter water cycle, leading to more rain than snow and causing premature snowmelt runoff.
Climate change poses a significant threat to winter snow levels, jeopardizing water supply reliability in the West. This situation demands an overhaul of our water infrastructure to adapt to a future unlike the past.
As spring 2026 approaches, Western states are experiencing a snow drought, with snowpack levels near historic lows due to unprecedented heat, increasing the likelihood of droughts, water shortages, and wildfires.
In California, where the Sierra Nevada snowpack accounts for nearly a third of the state’s annual water supply, an unusually warm winter and March heatwave have severely reduced snow levels. As water managers prepare for the April 1 snow survey, they are expected to find significantly below-average snowpack, aligning with long-standing climate science predictions of dwindling snow due to global warming.
What is a snow drought?
Despite early winter storms delivering over 90 inches of snow to the Sierra, the warm winter quickly depleted snow reserves. The early-season heatwave in March further exacerbated snow deficits, with temperatures soaring 20⁰F to 40⁰F above normal. This type of low snowpack, despite normal precipitation levels, is termed a warm snow drought. Recent research indicates that the Western US has become a global hotspot for snow droughts, which have increased in frequency and intensity over the past two decades compared to 1980-2000.
By early January, the snow water equivalent (SWE), a key snowpack indicator, was below the 20th percentile across the western US, marking the lowest level recorded since 2001. By late March 2026, conditions had not improved significantly. In Colorado, for example, the SWE was at 38% of average, the lowest in over 40 years.
In semi-arid California, the Sierra Nevada snowpack, often termed the “frozen reservoir,” is crucial for maintaining water supplies through dry and hot summers. Historically, snowmelt in late spring provides reliable water flow into rivers and reservoirs. However, climate change is shortening the window for snow accumulation, typically peaking on April 1, as the main snow-producing months—December through March—are affected.
Unrivaled: Snow is no match for winter heat
A March heatwave across Western North America was deemed “virtually impossible without human-induced climate change” by a World Weather Attribution study. This extreme heat followed an unusually warm winter, setting temperature records in states like Arizona, Colorado, and Wyoming, and causing more rain than snow at high elevations. The economic impact was significant, forcing ski resorts to end their seasons early.
In other areas, record-breaking warmth threatens outdoor winter sports, with organizations like Save Pond Hockey highlighting the challenges. A World Economic Forum report warns that by 2040, only 10 countries may have suitable winter weather for hosting the Winter Olympics, with significant financial losses looming for the sports sector.
Who’s the game changer? Climate change
Dr. Pablo Ortiz has previously discussed why snow is vital in California, describing it as an “indicator of climate change” and likening winter snow surveys to a “health check-up for our water system.”
Since the start of snow surveys at Phillips Station in 1942, the lowest recorded snowpack was in 2015, with only 5% of the historic average. This exceptionally warm winter, partly attributed to human activity, hindered snow accumulation and contributed to one of the most severe droughts on record.
The 2026 snow levels are closely watched, as early atmospheric rivers brought the snowpack to 89% of the average in January. However, a dry January, historically California’s wettest month, saw this drop to 59% by late January.
In the Northern Sierra, where some of the state’s largest reservoirs are located, the snowpack measured just 46% of normal by late February. Subsequent dry and warm conditions further reduced the snowpack by about 1% daily, according to state sensors. The heatwave accelerated this trend, with nearly 20% of the peak snowpack melting between late February and early March.
This rapid melting poses challenges for California, where winter precipitation has already filled major reservoirs to 122% of the average. This limits their capacity to handle additional early runoff and potential late-season storms, such as the upcoming weather.
Smaller snowpack may mean bigger wildfire risks
Record-high temperatures are drying vegetation, while reduced snowpack and early melt in the Western US are depriving soil of moisture, heightening the risk of wildfires. New research indicates that declining snowpack and earlier melt may lead to more severe fires, especially in areas where snowpack traditionally mitigated fire risks. Earlier snowmelt can also extend the fire season by providing a longer period for vegetation to dry and become flammable.
Climate change is accelerating wildfire activity in the West by affecting snowpack and melt timing, contributing to a near doubling of burned forest area between 1984 and 2015.
Contagious dry spells: Snow to hydrologic droughts
The western US has faced its driest two-plus decades in over 1,200 years. Though droughts are not uncommon, the current mega-drought is exacerbated by human-induced warming. Winter snow droughts can lead to hydrologic droughts, which are marked by decreased stream flow, reservoir levels, and groundwater, or to agricultural or ecological droughts that affect crops and ecosystems.
The Colorado River Basin, where snow cover is at a record low, supplies water to 40 million people. The concerns extend to hydropower generation, as the Glen Canyon Dam, providing electricity to over 5 million people, may become inoperable by December 2026 if water levels drop too low, according to government forecasts. Colorado’s snow drought prompted early water-use restrictions, with Denver Water urging a 20% conservation effort.
Snow drought consequences extend to water rights, as the Colorado River basin is already over-allocated. This winter’s snowpack may exacerbate ongoing water rights disputes, particularly affecting Tribal Nations with unresolved claims.
A common goal: Drought resilience is a long game
Despite California briefly being “100% drought free” following a wet winter, the National Weather Service’s Climate Prediction Center forecasts expanding drought in the US West and South-Central Plains this spring, according to NOAA.
Addressing a hotter, drier climate requires learning from past dry spells to improve adaptive strategies. After the 2021-2022 dry period, California overhauled its water management approach to better consider climate-driven changes to runoff, as misestimations led to significant runoff overestimations.
Since then, California has implemented forecasting improvements, but challenges remain in balancing summer water supply and spring flood risks.
The results from this week’s snow survey will guide California’s water management strategies in adapting to climate change.
Our Western States program is dedicated to a just land transition in California, aiming to enhance long-term drought and climate resilience through solutions that address current climate realities.
What can we do?
In areas like Denver, where communities are in a declared drought, residents are urged to monitor their water usage. On a broader scale, individuals can hold elected officials accountable for 1) protecting and preserving critical climate services provided by U.S. government institutions like the National Center for Atmospheric Research and 2) safeguarding democracy. As noted by Dr. Jennifer Jones, a shared commitment to knowledge and facts, free from political interference, is essential for maintaining democratic decision-making and enabling societal progress on major challenges, including climate change and public health. The UCS outlines five ways scientists can stand up to authoritarianism.
