The US Drought Monitor is updated weekly and is a synthesis of multiple indices and impacts that represents a consensus of federal and academic scientists. The US Drought Monitor is produced in partnership between the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC-UNL.

The US Drought Monitor is updated weekly and is a synthesis of multiple indices and impacts that represents a consensus of federal and academic scientists. The US Drought Monitor is produced in partnership between the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC-UNL.

The Palmer Drought Severity Index (PDSI) map from the Westwide Drought Tracker is updated monthly. PDSI is based on a simplified water budget that considers temperature, precipitation, and soil moisture data to determine the accumulated water excess or deficit. Negative values (yellow and red shades) show abnormal dryness to extreme drought. Positive values (shades of blue and green) indicate an excess of precipitation in an area.

VegDRI is updated bi-weekly and is a depiction of vegetation stress across the contiguous United States. The index is calculated using fine resolution satellite data combined with climate and biophysical data. Multiple factors such as climate, pests, land use change, fire, and extreme weather events can influence vegetation conditions, so including climate and biophysical data helps distinguish stress due to drought.

Departure from average greenness (DAG) maps are updated weekly using data from AVHRR satellite observations at a resolution of 1.1 km (0.6 mi). These maps portray how green each pixel of the image is compared to its average greenness for the current week of the year based on 1989-2003 data. Factors such as cloudiness, snow smoke, or haze can reduce the data quality.

Percent of 1981-2010 average precipitation by basin for the water year to date. Updated daily.

Snow water equivalent (SWE) percent of normal by basin based on 1981-2010 average. This product is updated daily with data from NRCS SNOTEL stations, and may not have data available in some locations in the summer and fall months.

Precipitation percent of normal by basin based on 1981-2010 average. This product is updated daily with data from NRCS SNOTEL stations.

Updated daily. Cumulative precipitation for northern Sierra 8-Station Index for current water year, past two water years, average, two driest years and wettest year on record.

Real time. This map shows real-time stream flow in the Great Basin. Yellow to red shades represent below normal stream flow, with bright red less than 10th percentile. Green shows normal flow in the 25-75th percentile. Shades of blue indicate above normal, and black represents the highest flows, greater than 90th percentile. This real-time stream flow map is meant to highlight flood and high flow conditions.

Updated daily. This map shows 7-day average stream flow in the Great Basin. Yellow to red shades represent below normal stream flow, with bright red less than 10th percentile. Green shows normal flow in the 25-75th percentile. Shades of blue indicate above normal, and black represents the highest flows, greater than 90th percentile. The 7-day stream flow map is used to highlight below-normal and drought conditions, rather than flood conditions.

Updated daily. This map shows average stream flow for the past 28 days in the Great Basin. Yellow to red shades represent below normal stream flow, with bright red less than 10th percentile. Green shows normal flow in the 25-75th percentile. Shades of blue indicate above normal, and black represents the highest flows, greater than 90th percentile. The 28-day stream flow map is used to highlight below-normal and drought conditions, rather than flood conditions.

Updated by 10th of each month. This graph from NRCS shows monthly reservoir storage as compared to capacity and average for states in the western US. The graph is updated each month January-May.

The First Leaf Index is based on the leaf-out of lilacs and honeysuckles, which are among the first plants to show their leaves in the spring. This Index is associated with the first leafing of early-spring shrubs and other plants. The anomaly maps indicate how a particular season "leaf-out" compares to an historic period (1982-2010).