Office of the Washington State Climatologist


Frequently Asked Questions

Washington's geography, especially the Cascade Mountain range, produces two vastly different climates in eastern and western Washington. Western Washington is often greatly influenced by the ocean, and is much wetter and milder than Eastern Washington. Additional stark differences are produced by the rain shadow effect of the Olympic Mountain range, so that for example Quinault has an annual average precipitation of 137" but in Sequim, only 56 miles away as the crow flies, the annual average precipitation is 16". For much more detailed information view the Climate of Washington Narrative.

A true statewide average requires accounting for the variation of temperature and precipitation in mountainous and other uninstrumented areas using statistical techniques, as is done with the PRISM dataset from Oregon State University:

  • Overall Temperature: 48.3°F
  • Maximum Temperature: 56.6°F
  • Minimum Temperature: 36.6°F
  • Precipitation: 45.70 inches

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There are a variety of sources online to obtain climate data for various purposes. Check out our Climate Data section for links to various information sources and graphics. And, if you don't find what you're looking for, or if you're not sure exactly what you're looking for, please contact us.

The OWSC, and other local and state agencies coordinate our efforts in assessing Washington's current and future state of drought with the Washington Department of Ecology. For the most up-to-date information go to the WA Dept. of Ecology Water Supply website.

For additional information go to:

Climate is what you expect.
Climate is usually defined as averages (and other statistics) of weather variables over some period of time, usually 30 years. Weather observations eventually turn into climate records. "Climate forecasts" are usually expressed as shifts in the statistics of weather over the next 1-12 months.

Weather is what you get!
Weather is described in terms of temperature, precipitation, cloudiness, wind speed, and so on. A description of these variables at any given moment constitutes weather; weather forecasts are much more specific than climate forecasts.

The world is unquestionably warming - the more difficult question to answer is whether human activity (chiefly the burning of fossil fuels like coal, oil, and natural gas) is responsible. Dozens of scientific studies have demonstrated that the increase in globally averaged temperature since about 1950 cannot be explained as a natural cycle or the result of changes in solar output or cosmic rays or volcanoes, but can be explained as a result of rising greenhouse gases. For detailed answers see

For a comprehensive look at climate change affecting Washington and the wider Pacific Northwest, view the Climate Impacts Group special reports and the Oregon Climate Change Research Institute latest assessment report.

A 100-year storm means that there is a 1% probability that the amount of precipitation that falls during a specified length of time, will be equaled or exceeded at a location for any given year. A 100-year storm on one day does nothing to change your chances of seeing the same amount of rainfall from a similar storm on another day (in the same year). Similarly, a 10-year storm has a 10% probability of occurring. To find the amount of precipitation that constitutes a 5, 10, 50 or 100 year storm view: Isopluvial Maps of Washington

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The average annual precipitation in Sequim and the surrounding area in the rain shadow of the Olympic Mountains (Port Angeles, Port Townsend, Whidbey and San Juan Islands) is lower than anywhere else in western Washington and in fact is lower than Sacramento, California! However, its location on the strait of Juan de Fuca ensures that summertime maximum temperatures rarely exceed 80 degrees and dew points are relatively high, so it does not feel dry the way Sacramento and other locations in the Southwest do. That's why houses in Sequim can grow moss on the roof (see photo 1,photo 2).

Find more information about the Olympic Mountain Rain Shadow including current monitoring efforts.

Resources for Locating Other Retirement Locations: