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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Current climate conditions & previous month's data
Expert knowledge, chaired by Dept. of Ecology
Predicted forecasts (based on accumluated data)
Data round-up of latest information from multiple agencies!

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

While eastern Washington received unusually warm and wet weather in November, western Washington had near normal temperatures and precipitation for the most part. Western Washington also notably experienced high winds, cold temperatures, and rainfall from the influence of an off-shore bomb cyclone on November 18 through 20, causing power outages, downed trees and other destruction. A bomb cyclone is defined as a pressure drop of at least 24 millibars within 24 hours. November’s bomb cyclone was assessed as a 27 millibar drop in pressure in just six hours. Averaged statewide, November was the 47th warmest (+0.7oF) and the 44th wettest (+0.81”) in the 130-year record. Although it is early in the season, snowpack is generally normal to above normal across Washington for this time of year.

Find details, updates on the U.S. Drought Monitor, an article on wind chill in Washington, as well as a climate summary and outlook in the December issue of the State Climatologist’s Newsletter.

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Climate Outlook, OWSC forecast:

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

According to the Climate Prediction Center (CPC), ENSO-neutral conditions are present in the tropical Pacific Ocean. Sea-surface temperature anomalies have remained below normal in the eastern tropical Pacific, neutral in the central tropical Pacific, and remained above normal in the western tropical Pacific Ocean. The latest ENSO models have delayed the onset of La Niña slightly, and models are now predicting development by the August-September-October period. The chances of La Niña during August-September-October are 70% compared to neutral conditions (29%). The developing La Niña is unlikely to have much of an effect on our summer weather, but will likely impact our weather by early fall.

What does this mean for Washington in the coming months?

The CPC one month temperature outlook for August indicates higher chances of above normal temperatures for a majority of the state. The odds are higher (between 40 and 50% on the three-tier scale) in eastern Washington. The Olympic Peninsula and southwest Washington have equal chances (~33% chance each) of below, equal to, or above normal August temperatures. The August precipitation outlook indicates higher chances of below normal precipitation across eastern Washington. Western Washington has equal chances of below, equal to, or above normal August precipitation.

The August-September-October (ASO) is also calling for equal chances of below, equal to, or above normal temperatures for a majority of the state. Southeastern Washington has a higher probability of above normal temperatures, with the odds between 33 and 40% on the three-tiered scale. For precipitation, there are higher chances of above normal precipitation for the Olympic Peninsula, southwestern Washington, and the northern Puget Sound region. The rest of the state is uncertain: there are equal chances of below, equal to, or above normal ASO precipitation.

Last Updated: 7/18/2024

Data round-up: drought conditions summary

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

La Niña is here, as of January 9th. However, it is weak and very late. While La Niña usually means wetter and colder, weak and late means less of an impact on our temperature and precipitation (CPC: ENSO Diagnostic).
January is early for statewide predictions
However, the Yakima Basin and Central Cascades, are an area of particular concern for drought recovery and compounding deficits after back-to-back droughts in 2023 and 2024. While the statewide SWE (snowpack measurement) map shows better overall averages, there are individual SNOTEL (snow measuring) sites that are at less than 50% of average snowpack for this time in January. Bureau of Reclamation reservoirs are also at 35% of average storage level, for this day in January (compared to 30-year normals). This is a concerning storage level in order to fill the gap in storage from the beginning of the water year, in October 2024.

The Washington State Climate Office summarized data. Forecast can be found here as well: Climate Outlook & newest Newsletter

Mean December temperatures were much above normal across Washington State, with the greatest temperature anomalies in eastern WA. Averaged statewide, December ranked as the 10th warmest in the 130-year record, with average temperatures 4.0°F above the 1991-2020 normal.
Lowland snow was nonexistent in western WA due to the above normal temperatures.
Last updated: January 14 (newsletter); Next update (monthly): Mid-February

According to National Resources Conservation Science & U.S. Department of Agriculture

SWE Map – NWCC iMap
84% Statewide (down 8% from last week, down 20% from two weeks), compared to Normal Snow Water Equivalent (SWE); By Basin: WA Report or by maps: SWE by Basin – PDF (attached) or Interactive map
84% (down 3% from last week, down 6% in the last two weeks) = Water YTD precipitation.
Last updated: January 27;
Next update (daily): January 28. (Why does “SWE” matter – USDA Factsheet).

Bureau of Reclamation data and information updates:

Yakima River system (Keechelus, Kachess, Cle Elum, Bumping, Rimrock) is at 18% of capacity and storage is at 34.5% of average.
Last updated: January 27; Next update (daily): January 28.

Northwest River Forecast Center data and informaiton updates:

10 Day Meteorological Forests – Precipitation to return to in the latter half of the next ten days, statewide in latter end of that, but temperatures may not be as cold as we would like in the mountains for drought recovery.
Forecast report and Forecast map – Additional areas now on the Olympic Peninsula and parts of SW, plus prior areas in Okanogan, North Central & SE areas have April-Sept forecast below 75% (although this is still quite early for major predictions).
NOTE: April – Sept forecasts are based on the next 10 days of forecast data, then based on climate Normals from 1991-2020 average.
Lasted updated: January 27; Next update(daily): January 28.
Next update(daily): January 14.

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

8-14 day Outlook: Higher likelihood of below normal temps statewide; with leaning toward above normal precipitation in parts of Central and Eastside.
- Valid: Feb 3-9, 2025, Issued: Jan 26, 2025
Three-month Temperature and precipitation outlook (February-March-April):
- Temperature: Probability slightly leaning towards below normal.
- Precipitation: Probability slightly leaning towards above normal.
- Last updated: Issued January 16 2024; Next update (monthly) January 16, 2024.

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

For PNW: Washington | Drought.gov
National Drought Monitor – Continued "D1" drought in the Central Cascades and Yakima Basin with increased D1 status in areas on the eastern flank of the Cascades, central and northern.
Reminder: Tool does not account for anticipated impacts on water supply from snowpack.
Updated: The U.S. Drought Monitor map is released every Thursday morning, with data valid through Tuesday at 7 am Eastern.

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

National Water Dashboard – Additional areas with significantly below normal streamflow (red dots) or below normal (orange dots) in SW, across the Westside, NW, and Central, with scattered below normal streamflow in all regions.
Last updated: January 27 Next update (daily): January 28.

Other data tools utilized, updated:

Odds of 2024 Water Year Precipitation Reaching 100% - Central and North Cascades - Odds between 25-50% for reaching 100% of normal precipitation for water year 2025.
Climate Mapper – Mean Temperature & Precipitation Anomaly- Last 30 days - Much of the state had temperatures significantly above Normal; precipitation below normal on the Westside and NE of the state, and above normal on much of the Eastside.
PRISM Palmer Drought Severity Index – Continued drought concerns for central areas of the state.

Contact information

Caroline Mellor
Statewide Drought Lead
caroline.mellor@ecy.wa.gov
360-628-4666