What to know about the Kelvin wave raising the sea level along the West Coast

Sea levels along the U.S. West Coast are expected to rise by up to about a foot this month as Kelvin waves—pulses of warm water—move north after hitting the shoreline. The surges are not tsunamis and won’t be seen, but they can lift the baseline sea level, making high tides, storms, and storm surges more damaging in places already affected by climate change and El Niño. The wave, roughly 6 inches to 1 foot tall, is forecast to travel up the California coast at about 6 miles per hour and continue affecting the region from October through February. Experts also note impacts on ocean temperatures and marine life.