Heavy rain and blizzards aren’t the only forms of severe weather Waymo’s self-driving vehicles encounter on the regular. In a blog post published this morning, the Alphabet subsidiary laid out the ways its cars in over 25 cities tackle fog, dust, smoke, and other dangerous conditions that trip up even human drivers.

“Challenging [environmental] conditions, which affect human driver and vehicle performance, are one of the leading contributors to crashes on our roads … Poor perception creates significant risk for other road users including pedestrians, cyclists, and other vehicle occupants,” wrote Waymo chief safety officer Debbie Hersman. “Waymo is working hard to master a variety of weather scenarios as part of our mission to improve road safety.”

To this end, Waymo says its autonomous vehicles are designed to detect sudden extreme weather changes, such as a snowstorm, that could impact their ability to drive safely. If conditions deteriorate below a certain threshold, they come to a safe stop until things improve.

Some experts believe this sort of situational awareness will play a critical role in the safe deployment of driverless cars globally. For its part, Waymo rival and GM subsidiary Cruise is testing computer vision and sound detection AI to help driverless vehicles pause for passing police cars, fire trucks, ambulances, and other emergency vehicles.

That said, Waymo’s cars are remarkably robust. In Arizona, where intense dust storms (known as haboobs) aren’t uncommon, its cars’ systems tap radar and lidar to spot other road users even when camera visibility is extremely limited. (Waymo’s sensor stack includes five custom-designed lidars that bounce light off of objects to map them three-dimensionally, along with five front- and side-facing cameras and the aforementioned radars.)

“While self-driving cars and human drivers alike are limited by the performance capabilities of the vehicle itself, and there are environmental conditions that no driver, human or technology, should drive in, AVs have the potential to improve one of the greatest performance limitations: visibility,” added Hersman.

It’s been a newsy week for Wa