Google's driverless car testing has logged more than a million miles on the road, but there's one thing they may not have come across in all those hours of driving which could pose quite a big challenge, especially if they were to come to Britain's roads: rain.
The self-driving cars will now hit the streets of a new location to test its metal against the elements.
Kirkland in Washington State close to Seattle has rainy seasons and more hills than the roads of California and Texas where the cars have been tested for the past few years and since last summer, respectively.
Jennifer Haroon, Google's head of business operations for its self-driving cars division, told the Seattle Times said the location will give it a chance to test the impact of rain.
While the development of driverless car technology has recently picked up the pace, rain is one of several obstacles that still lays in the way of a fully autonomous future.
In 2014, the head of Google's driverless car plans, Chris Urmson, outlined some of the challenges it still faced, including rain, snow and even bright sunlight. But since then its been working on such challenges to hit Urmson's goal of having the tech ready for his then 11-year-old son to drive when he hits 16.
In its December update on driverless cars, Google said: "Our laser sensors are able to detect rain, so we have to teach our cars to see through the raindrops and clouds of exhaust on cold mornings, and continue to properly detect objects. We’re helped by our diversity of sensors, since our radars have no problem seeing through this sort of clutter."
"As we’re developing the technology, we've made sure our cars are aware of how rain may affect their ability to drive. Our cars can determine the severity of the rain, and just like human drivers they drive more cautiously in wet conditions when roads are slippery and visibility is poor."
And if it's particularly stormy the cars will pull over and wait for conditions to clear.
Now those technical details will be put to the test with the goal of overcoming one of the biggest challenges to driverless cars in Britain thanks to its usually less than sunny climate.