Eclipse chasers don’t like to use the C-word, but they do have to consider the possibility, of course. If it’s cloudy, you won’t see what you will see if it’s clear – simple as that.
For those in the path:
If the sky is completely overcast, it will get VERY dark – pitch black, in fact, to the point where it will be tricky to walk around.
If there are broken or scattered clouds, then you will have to hope that the Sun is not behind one of them at the time of totality. If you can re-position yourself to spot where the Sun will be in the clear during totality (this is the REAL “eclipse chasing”!), then you will be able to see the Diamond Ring, the corona, and all the cool effects that present during totality.
If the Sun is behind a cloud during totality, you will still experience the temperature drop, and the sunset glow on the horizon – but this is not how you want to see a total eclipse!
What veteran eclipse chasers do is to plan for a viewing location that historically has given signs of having as few clouds as possible on eclipse day. But we’re still subject to the whims of weather, and so mobility on eclipse day is very important.
It’s not unusual for die-hard eclipse chasers to keep airplanes on standby, in case they have to make a last-minute run for it to escape clouds! With mobility as easy as it is in the USA, though, we should be able to look at forecasts a day or two before, and move accordingly to try and get into a path location that promises to be cloud-free.
Remember that most eclipse chasers think nothing of going into the remotest parts of the world – a little diversion such as having to relocate to Wyoming from North Carolina is NOTHING compared to the wonder of seeing a total eclipse! Again, after you see it, you will understand why.