Hazard warning: slow down and proceed with extreme caution on road ahead

Where you will see it

On a stretch that is dangerous for reasons the sign itself does not spell out.

What to do

Come down to a speed you could stop from inside your own line of sight, and keep both hands on the wheel. Where a sign asks for extreme caution and names no reason, treat the usual ones as live: people, animals, a broken surface, a vehicle stopped in your lane.