Monthly Statewide Conditions

 Monthly Water Supply Summary

This webpage contains both state-wide and individual river basin summaries, which include interactive maps and plots so that current conditions can be quickly viewed.

To view the state-wide summary, continue scrolling through the page below. Links to the individual river basin summaries can be found at the bottom of this webpage, or by using the top navigation bar and hovering over the "Water Supply Tab" and dropping down to "Monthly River Basin Summaries".

Weather and Climate for the Previous Month

Data provided below is courtesy of the West-Wide Drought Tracker which produces these maps during the first week of each month. Data is based on the PRISM dataset, which incorporates both mountain SNOTEL and valley weather stations (COOP/ACIS). 


NRCS Monthly Maps and Data

(Snowpack, Precipitation, Reservoir Storage and Streamflow Forecasts)

All maps shown below are interactive. Select individual basins to view the basin totals, view sites used in the calculations, or download data. In addition to the basin data, you can also select individual SNOTEL sites, snowcourses, reservoirs and streamflow points to view information related to the metric selected in the menu bar.  


NRCS Basin Reports (All Data Points)

(Snowpack, Precipitation, Reservoir Storage and Streamflow Forecasts)

The tables shown below default to the 1st day of the current month. Much of the data that populates these reports is manually collected around the 1st day of each month. Consequently, the reports will continue to update and change during the business week, but data is typically finalized by the 5th business day of each month. Reports are available for snowpack, precipitation and reservoir storage on a monthly basis. Streamflow forecasts, which are issued March 1st through June 1st, will be available by the 5th business day of each month during that time period. 

To view previous reports, or to view daily reports, please visit the "SNOTEL Update Report" web page.     


Current Drought Status

 (Source: National Drought Information Center - NIDIS)


Long-Range Weather Outlooks

(Source: NOAA-CPC )

Long-Range Outlooks are provided to the public by NOAA's Climate Prediction Center for Temperature and Precipitation. Forecasts are issued for probability of temperature or precipitation being above or below average for the period. Put in simpler terms, the darker the color is, the higher the probability of occurrence is during the forecasted period.

One Month Outlook

 Seasonal Outlook (3 months)


River Basin Summaries

Columbia River Basin Missouri River Basin Yellowstone River Basin
Kootenai Jefferson Upper Yellowstone
Flathead Madison Bighorn-Powder-Tongue
Upper Clark Gallatin  
Bitterroot Helena Valley  
Lower Clark Smith-Judith-Musselshell  
  St. Mary