Your Real-Time Eye on San Francisco's Famous Fog

It’s cold and cottony, sails over the city like the gloomy mist preceding a ghost invasion, and even has a name, “Karl”—San Francisco’s lovely fog, arriving each summer to smother the horizon and the hopes of sun-loving beachgoers.

Now locals and anyone worldwide can check in on Karl’s current condition thanks to Fog Today, which pulls detailed scans from NOAA’s new geostationary Earth-observation satellite, GOES-16. The site presents static images taken with the last five to 10 minutes and also loops from the previous day, so you can watch the fog spread silently, but often explosively, over the coastline and into the San Francisco Bay. (Unfortunately it does not process nighttime images, because the dark-induced noise makes it look like locusts are overrunning the city.)