Cloud does more than hide the sun. It changes contrast, dampens sound and can expose a single illuminated shoulder while the rest of the valley disappears.
Visibility is also a road condition
That same mist shortens visibility on bends and wets unpaved shoulders. A disappointing horizon is never a reason to stop a vehicle in an unsafe place.
Carry a rain layer and protect the camera, but avoid turning the visit into an unguided walk when the recognised point is unclear.
What to notice on the ground
Listen as well as look. Bird calls, dripping leaves and the movement of cloud can make a quiet dawn specific even without a broad panorama.