Slippery When Wet Sign
MUTCD W8-5
The road is slippery when wet; slow down and drive carefully.
What it looks like
A yellow diamond-shaped warning sign, often showing a black car symbol with curved skid lines, or the legend SLIPPERY WHEN WET.
When you'll see it
On bridges, curves, and stretches of road that lose traction in rain, or where oil and moisture make the surface slick.
What to do
Slow down and drive carefully when the road is wet; brake gently, increase your following distance, and avoid sudden steering.
Related signs
Source: Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition — FHWA.