Statewide conditions

As the state's lead agency for water supplies, we pay close attention to multiple data sources and monitor them closely. Here you can find:

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What is WSAC?

The Water Supply Availability Committee (WSAC) is a group of experts from state and federal agencies who evaluate statewide water supply conditions. Ecology chairs this group that provides an important consultative role to Ecology. WSAC advises Ecology on current and forecasted water supply conditions and whether the hydrologic drought threshold has been met or is likely to be met: seventy-five percent of normal water supply within a geographic area (RCW 43.83B.405 and WAC 173-166-050).

If you would like to receive notices about WSAC meetings after they are posted to this page, subscribe to the Washington Water Supply Email list.

Tacoma Old Town Dock. Photo by Wayne Hsieh, https://flic.kr/p/2pBqtCX

The Office of the Washington State Climatologist (OWSC) serves as one credible and expert source of climate and weather information for the state. Their monthly newsletter reviews the previous month’s data and details, as well as an introduction to the Natural Resources Conservation Service’s Snow and Water Interactive Map (iMAP), climate summary and outlook, and a link to reporting your observed drought impacts. Check out our Water Supply Monitoring page for additional sources. 

Summary of recent conditions

April temperatures in Washington averaged near normal to below normal statewide, while precipitation was below normal. Snowpack is only 53% to 69% of normal for most of the state. Due to the low snowpack and expected warm and dry spring and summer, a drought emergency has been declared for most of the state. Small areas around Everett, Seattle, and Tacoma are excluded as the water utilities serving those areas expect to have sufficient water supplies.

Check out the 4th Pacific Northwest Water Year Impacts Assessment as well, which reports on different sector-specific impacts caused by varying temperature, precipitation, and snowpack in the 2023 water year (October 2022 through September 2023). In general, Washington was slightly drier than normal, but looking only at broad averages masks the seasonal and area variability. What caused the largest impact was the rapid snowpack melt in May 2023, the warmest May in the 129-year record

Climate Outlook, OWSC forecast:  

El Niño-Southern Oscillation (ENSO): El Niño currently, La Niña likely by late summer

According to the Climate Prediction Center (CPC), El Niño in the tropical equatorial Pacific Ocean is continuing to weaken and the transition to neutral conditions is expected very soon. The latest ENSO models show a transition to neutral conditions during the April-May-June period (79% chance). A “La Niña Watch” has been issued because there are higher chances of La Niña (69%) by the July-August-September period compared to neutral (30%), and the likelihood of La Niña increases into next fall and winter. The developing La Niña is unlikely to have much of an effect on our summer weather.

What does this mean for Washington in the coming months?

The CPC one month temperature outlook for June indicates higher chances of above normal temperatures statewide. The odds of above normal temperatures are between 40 and 50% on the three-tiered scale. The June precipitation outlook indicates higher chances of below normal precipitation across the state.

The three-month summer outlook (June-July-August; JJA) has a high probability of above normal temperatures across all of Washington State, with the odds between 40 and 60% on the three-tiered scale depending on location. For precipitation, there are higher chances of below normal precipitation statewide. The chances of below normal JJA precipitation are between 40 and 50% for a majority of the state.

Last Updated: 5/17/2024

Data round-up: drought conditions

This is a snapshot of wide variety of data sources that helps Ecology to understand evolving drought conditions. This will be updated weekly. 

The Office of Washington State Climatologist's summarized data. Forecast can be found here as well:

  • New: The April Outlook indicates outlook for May indicates higher chances of above normal temperatures statewide. El Niño is still present in the tropical equatorial Pacific Ocean, but is continuing to weaken. The developing La Niña is unlikely to have much of an effect on our summer weather.
  • April summary: Mean April temperatures were near-normal to below normal across Washington State. April precipitation was below normal for nearly the entire state. Temperatures were cooler relative to normal than they were in March, but precipitation was much lower relative to normal.
  • Last updated: May 2, 2024; Next update (monthly): Mid-June

According to National Resources Conservation Science & U.S. Department of Agriculture, 60% Statewide (Down 2% from last week) Snow Water Equivalent (SWE); By Basin: WA Report or by maps: SWE by Basin – PDF or Interactive map

  • 87% = Water YTD precipitation (Down 1% from last week).
  • On this date in 2015, Statewide SWE was 15% and Water YTD precipitation was 93%.
  • Reminder for Basin numbers: The Lower Snake-Walla Walla, Lower Pend Oreille and Spokane SWE Basin numbers include stations in Oregon and Idaho.
  • Why does “SWE” matter – USDA Factsheet
  • Last updated: May 20 – now end of day; Next update (daily): May 21.

Bureau of Reclamation data and information updates:

  • Yakima River system (Keechelus, Kachess, Cle Elum, Bumping, Rimrock) is at 63% of capacity and storage is at 74.7% of average.
  • Last updated: May 20, 2024; Next update: May 21 (daily).
  • May 3 BOR forecast: The U.S. Bureau of Reclamation (BOR) projected Monday that Yakima River basin irrigators with junior water rights will receive 54% of their full allotments between April and September. Allotments could drop to as little as 46% if the weather is dry and warm.

Northwest River Forecast Center data and informaiton updates:

  • 10 Day Meteorological Forests – Minor precipitation in the next few days in the Westside, with Minimal to none precipitation in the following week. Normal temperatures for many regions of the state. Spring likely to turn towards summer in much of the state in the later half of the next ten days.
  • Forecast report and Forecast map – Areas in the  North & Central Puget Sound, Okanagan, Methow, Wenatchee, Upper Columbia and Spokane with streamflow forecast below 75%, with some below or nearing below 50% of normal (screenshot of natural forecast)
  • Streamflow Water Supply forecast – Ranking based on comparison to historical record – The attached screenshot highlights that areas are forecasted to rank among the lowest years measured.
  • Streamflow forecasts: Chelan River is forecasted at 61%; Stehekin at 68%; Methow at 75%, Okanagan at 49% and Skagit at 68% for April to September.
  • Lasted updated: May 20; Next update(daily): May 21.     

National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS) and Climate Prediction Center (CPC) data update:

  • 8-14 day Outlook: Temperature: Slightly probability of below normal temperatures with precipitation at slightly above normal for the Western part of the state.  
    • Valid: May 27-June 2, 2024, Issued: May 19, 2024
  • Three-month temperature and precipitation outlook (June-July-August):
    • Temperature: Likely above normal temperatures (probability 50-60%).
    • Precipitation: Leaning below normal (probability 40-50%).
    • Last updated: Issued May 16, 2024; Next update (monthly) June 20, 2024.

National Integrated Drought Information System (NIDIS) latest collected data and outlooks: 

United States Geological Survey (USGS) data collected by WA Water Science Center:

  • National Water Dashboard – Worsening: Additional areas are now in orange (below normal) with areas now in red (significantly below normal) for streamflow status, with areas in all regions.
  • Last updated: May 20 2024; Next update: May 21 (daily).

Other data tools utilized, updated:

  • Odds of 2024 Water Year Precipitation Reaching 100% - Below 40% for much of the state.
  • Climate Mapper – Mean Temperature & Precipitation Anomaly- Last 60 days – Multiple levels above normal for temperature and below normal for precipitation.
  • PRISM Palmer Drought Severity Index – “5” out of 6 negative scale on drought severity for parts of the Olympics, North and Central Cascades and NE and SE WA (“based on a simplified water budget that considers water supply (precipitation), demand (evapotranspiration) and loss (runoff)”). Updated monthly, January most recent.