SAN FRANCISCO (CBS SF) — T’is the season for foggy afternoons as spring blossoms into summer around the San Francisco Bay Area.

Warmer temperatures in the Central Valley send hot air rising as the heavier cold ocean air rushes in to replace it. This flow pulls fog through the Golden Gate Bridge and sends it swirling over the city skyscrapers and the Marin Headlands.

We’ve rounded up some of our favorite photos from the last week capturing this beloved Bay Area phenomenon, a signal that summer is right around the corner: