sUAV's fly under VFR rules.
That means visibility minimums, ceiling requirements and NOT FLYING INTO OR NEAR CLOUDS
Below 1200 AGL it is 1 statute mile visibility and stay clear of clouds
The basic VFR weather minimums are specific to types of airspace and altitudes.
Does the concept of "see and avoid" ring a bell? VLOS?
Not that many of us get to 1200 AGL, but the rules for there are
500 below 1,000 above 2,000 horizontal away from clouds. That means don't fly into them!
Remember the FAA has a very broad policy allowing for prosecution if a flight was unsafe, even IF it followed the rules.