Google's self-driving cars are cruising into a new destination: the Valley of the Sun.

The Web giant on Thursday announced it has selected the Phoenix metro area as the next location for its self-driving car testing program. Phoenix is now the third location outside of Google's hometown of Mountain View, Calif. where regular testing will take place.

Over the last nine months, Google has expanded its testing program to Austin, Texas and Kirkland, Wash., but said Phoenix will offer a different driving environment, traffic patterns, and road conditions than its cars have seen.

"This new location will give our cars a chance to practice driving in a desert environment — and experience handling some of Phoenix's quirks, like cacti, golf cart crossings, and time-based speed limits," according to a post on the company's self-driving car project Google+ page.

That desert environment will also help Google better understand how its sensors and cars can handle extreme temperatures and dust in the air, according to Jennifer Haroon, head of business operations Google's self-driving car project.

"Driving in new cities enables our engineers to further refine our software and adapt to these different environments," Haroon said in a statement.

Over the past few days, Google's test drivers have been cruising around in four Lexus RX450h SUVs creating a detailed map of the streets around the Phoenix area. They're noting things like lane markers, traffic signals, curb heights, and "keep clear" zones to help the car understand where it is, and things to look out for.

"Soon our car will be ready to autonomously drive (with a test driver onboard and able to take over, if needed)," Google said.

To date, Google's self-driving cars have driven 1.5 million autonomous miles — and only caused one accident so far. Sensors on these vehicles can detect "hundreds of distinct objects simultaneously in a small area," Google said, including pedestrians, buses, stop signs held up by crossing guards, and cyclists making gestures to indicate a turn.

Google maintains that self-driving cars have the potential to improve road safety, reduce traffic, and offer new freedom for those who can't drive.