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Snow Drought

Snowpack typically acts as a natural reservoir, providing water throughout the drier summer months. Lack of snowpack storage, or a shift in timing of snowmelt from that reservoir, can be a challenge for drought planning. Snow drought is a period of abnormally little snowpack for the time of year. Recent research shows that the western U.S. has emerged as a global snow drought “hotspot,” where snow droughts became more prevalent, intensified, and lengthened in the second half of the period 1980 to 2018.

Read the Latest Snow Drought Update

Types of Snow Drought

There are two types of snow drought based on the AMS Glossary of Meteorology:

A ruler buried in snow
Dry snow drought

Below-normal cold-season precipitation

A forest with some partially melted patches of snow
Warm snow drought

A lack of snow accumulation despite near-normal precipitation, caused by warm temperatures and precipitation falling as rain rather than snow or unusually early snowmelt.

Data, Maps, and Tools

Few drought metrics include storage and release of snow water. Several years of low snowpack, especially across the western U.S., have led to studies examining the causes and impacts of reduced snow storage and seeking a new definition for snow drought.

Snow Drought Conditons

This USDA Natural Resources Conservation Service (NRCS) map shows Snow Telemetry (SNOTEL) snow water equivalent (SWE) basin values over the western U.S. as a percent of the NRCS 1991–2020 median. Only stations with at least 20 years of data are included in the station averages.

The SWE percent of normal represents the current snow water equivalent found at selected SNOTEL sites in or near the basin compared to the average value for those sites on this day. This map is valid through May 24, 2022.

Learn more.

This map shows SNODAS snow water equivalent (SWE, the amount of liquid water contained within snowpack) for the past two days, as a percent of the 2004–2021 average. The SNOw Data Assimilation System (SNODAS) is a modeling and data assimilation system developed by NOAA's National Operational Hydrologic Remote Sensing Center (NOHRSC) to provide the best possible estimates of snow cover and associated parameters to support hydrologic modeling and analysis. Learn more.

Snow Water Equivalent (SWE) Percent of NRCS 1991–2020 Median
Range Map Hex Color
0% - 50% #e80000
50% - 70% #e39a00
70% - 90% #e6e500
90% - 110% #4ee504
Range Map Hex Color
110% - 130% #70ffdd
130% - 150% #00a9e4
150% - #0100fe
Value Map Hex Color
No basin value #767676
SWE Percent of Normal (%)
Range Map Hex Color
0 - 0.01 #ffffff
0.01 - 5 #543005
5 - 25 #8c510a
25 - 50 #bf812d
50 - 70 #dfc27d
70 - 90 #f6e8c3
90 - 110 #8a8a8a
Range Map Hex Color
110 - 130 #c7eae5
130 - 150 #80cdc1
150 - 200 #35978f
200 - 400 #01665e
400 - 800 #003c30

Impacts and Related Content

Summer Water Availability

Snow droughts reduce the amount of available water for spring and summer snow melt. This, in turn, reduces or shifts the timing of streamflow and reduces soil moisture, which can have impacts on water storage, irrigation, fisheries, vegetation, municipal water supplies, and wildfire.

Winter Water Management

Warmer winter storms lead to rain instead of snow at higher elevations in mountain regions. This can create challenges for water management and flood mitigation strategies, particularly when dealing with extreme events.

By Sector | Recreation and Tourism

Many local economies and industries rely on snowpack and river flows from snowmelt to support their outdoor industries, such as skiing, rafting, and fishing.

Research & Learn | Snow Drought

Find more detailed information about snow drought, including the importance of snowpack and snow drought’s impact on ecosystems, water supply, and local economies.

The Great Western Snow Drought of 2015

The winter of 2015 brought unusually warm temperatures to the western United States and serves as a classic example of how warm temperatures can cause snow drought. By April 1, not a single basin in the West was above 86% of median snow water equivalent—and most basins in Washington, Oregon, California, Nevada, Utah, and Arizona were below 40%.

The Rocky Mountains covered in snow and trees

Snow Drought Research and Resources