Projections & Maps

Projected Sea Level Rise in Seattle

By 2050, there is a 50% chance of at least 0.8 feet of SLR in Seattle. This means that our monthly high tides will be 2 feet higher than today’s average monthly high tide (known as Mean Higher High Water or MHHW). King Tides will be 3 feet higher than today’s MHHW, and storm surges could be 4 feet higher than today’s MHHW.

By 2100, projections show between 2.4 and 5.2 feet of SLR in Seattle. If we consider 3 feet of rise, then monthly high tides will be 4 feet higher, King Tides will be 5 feet higher, and storm surge could be 6 feet higher than today's MHHW.

For further information about SLR projections in Washington, you can watch this 13 minute video, in which Ian Miller, Coastal Hazards Specialist with Washington Sea Grant, discusses findings of the 2018 Washington Coastal Resiliency Project.

How We Measure Sea Level Rise

Sea level refers to Mean Higher High Water (MHHW) level of 9 feet on the North American Vertical Datum of 1988 (NAVD88). The Sea Level Rise Map refers to sea level rise in the following way:

• 2 feet of SLR = 11 feet NAVD88
• 3 feet of SLR = 12 feet NAVD88
• 4 feet of SLR = 13 feet NAVD88
• 5 feet of SLR = 14 feet NAVD88

Seattle’s SLR projections and scenarios are based on the 2018 Washington Coastal Resiliency Project (WCRP) by Miller et al. (2018). They are Washington-specific SLR projections based on climate models from the IPCC’s fifth assessment report (Church et al.2013). For more information about these projections, and for extensive documentation on the methodology used, please visit the University of Washington Climate Impacts Group website.

Sea-Level Rise ("SLR") information is prepared for use by The City of Seattle for its internal purposes only, and is not designed or intended for use by members of the public. ALL SUCH SLR INFORMATION AND CONTENT IS PROVIDED ON AN "AS IS", "AS AVAILABLE" BASIS WITHOUT WARRANTIES OF ANY KIND EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, ACCURACY, AND NON-INFRINGEMENT. The City of Seattle makes no representations or warranty as to its accuracy, and in particular, its accuracy as to labeling, completeness, reliability, currency, dimensions, contours, property boundaries or placement of location of any map feature thereon. In no event will The City of Seattle be liable for any loss or damage including without limitation, indirect or consequential loss or damage, or any loss or damage whatsoever arising from loss of data or profits arising out of, or in connection with, the use of any SLR information.