Carpets of yellow, orange and gold flowers are beginning to cover Southern California’s vast deserts, the Bay Area’s dramatic bluffs and even near Los Angeles International Airport.

But do they add up to a “superbloom”? There is no single definition of the event, but so far this year’s blooms haven’t been as vibrant or abundant as those that took over swaths of California last spring following drought-busting rains. This year, too, the state received ample winter rains.

After especially wet winters, bursts of color may appear in the spring, drawing droves of visitors to California and other parts of the Southwest to glimpse the flowering fields and pose for pictures.

Here are some key facts about the natural spectacle:

WHAT’S A SUPERBLOOM?

Scientists don’t agree on any one definition. Across California and Arizona, there are stretches of desert that can quickly transform into dense fields of wildflowers, since seeds lie dormant in the soil and then germinate and blossom at around the same time.