Tide gauges and satellites
Sea level along the coast
Each gauge's level with the tide taken out, a week's mean, against its past year; or, over ten days, hour by hour against the tide. How it is worked out
Six months along the coast
Each lane is one tide gauge, San Diego at the front and Kodiak Island 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.
This season beside the strongest El Niños
San Diego's sea level each month, from June into the following spring, against its usual level for that time of year, with the long-term rise taken out: this season beside 1982–83, 1997–98 and 2015–16. Months NOAA has not yet verified are averaged from its preliminary readings and drawn hollow. This compares what was measured; it does not say what comes next.
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. Gauges from the equator to Central America: University of Hawaii Sea Level Center fast delivery data, through 31 August 2026 (Caldwell, P. C., M. A. Merrifield and P. R. Thompson, 2015, Sea level measured by tide gauges from global oceans, the Joint Archive for Sea Level holdings, NCEI Accession 0019568, doi:10.7289/V5V40S7W). 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 ocean view 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; the gauges at the Galápagos, in Ecuador and in Central America see it first. Out on the islands of the western Pacific, at Guam and Kwajalein, sea level usually falls instead, as the warm water heaped up there drains east. 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.