Tide gauges and satellites
Sea level along the Pacific coast
Each tide gauge's water level with the tide taken out, averaged over a week and compared with its usual level (its average over the past year). The pale line is that usual level: a dot above it means the sea is higher than usual, below it lower. Between gauges the band is filled in from the nearest two, except across gaps over 600 km. Offshore, faintly: satellite sea level, compared the same way and smoothed; it still includes the seasons. How it is worked out
Six months up the coast
Each lane is one tide gauge, San Diego at the front and Kodiak at the back, spaced as they are along the coast; time runs left to right. Points above the glass sheet are days when the sea stood higher than usual, points below it lower. A high or low takes only days to travel up the coast, so on six months it crosses the lanes almost straight, leaning slightly later toward the back. Drag to turn the view; the replay above shows it day by day.
Tide gauges: NOAA CO-OPS and the Canadian Hydrographic Service. British Columbia's gauges contain intellectual property (Data) of the Canadian Hydrographic Service; copyright His Majesty the King in Right of Canada. Not for navigation. Satellite sea level: NOAA CoastWatch, from RADS; Sentinel data courtesy of the Copernicus Programme; generated using AVISO+ products.
Why the sea stands higher for weeks
When the trade winds along the equator weaken, a bulge of warm water crosses the Pacific eastward as an equatorial Kelvin wave; on the globe, switch to the Pacific to see the satellites' sea level along the equator. Reaching the Americas it turns and runs along the coast as a coastally trapped wave, raising sea level and warming the water for weeks as it passes. Wind along the coast and air pressure make swings like these too, and north of Washington the gauges' swings are mostly the weather's. This page shows them all, as they were measured, and does not say which is which; it does not forecast what comes next.