What does the Slippery When Wet sign mean?
The Slippery When Wet sign (MUTCD W8-5) is a warning sign under the federal Manual on Uniform Traffic Control Devices, the national standard the states build from. Grip falls away sharply on this stretch once it is wet, so brake, steer and accelerate one at a time and none of them hard.
Source: MUTCD 11th Edition, Chapter 2C, Table 2C-1, checked 2026-09-09.
What shape and color is the Slippery When Wet sign?
| MUTCD code | W8-5 |
|---|---|
| Group | Warning signs |
| Shape | Diamond |
| Color | Yellow background, black car-and-skid-marks symbol and border |
What a diamond means. A warning. It tells you what the road does next and obliges you to do nothing in particular, which is the distinction test writers probe most often.
What yellow means. General warning of a permanent condition ahead.
Warning signs. A diamond reports a condition and orders nothing. What you do about it is left to you, and that gap between a report and an order is what test writers keep probing.
What is the Slippery When Wet sign often mistaken for?
Bridge Ices Before Road (W8-13), which is a specific cold-weather hazard, and Grooved Pavement (W8-15), which mainly affects motorcycles.
|  |
|---|---|
| GroupWarning signs | GroupWarning signs |
| ShapeDiamond | ShapeDiamond |
| ColorYellow background, black car-and-skid-marks symbol and border | ColorYellow background, black legend and border |
| What it meansGrip falls away sharply on this stretch once it is wet, so brake, steer and accelerate one at a time and none of them hard. | What it meansThe bridge deck freezes earlier than the surrounding roadway because cold air passes underneath. |
What does the permit test ask about the Slippery When Wet sign?
These 2 questions are from the practice bank, with the answer marked.
This sign warns that the road ahead:
- A.Floods in heavy rain
- B.Loses grip when wet, so slow down before you need to brake(correct answer)
- C.Is under construction
- D.Has loose gravel
Source: MUTCD W8-5
The most slippery road conditions usually occur:
- A.After several hours of heavy rain
- B.In the first few minutes of rain after a dry spell(correct answer)
- C.Only when the temperature is below freezing
- D.During fog
Why: Oil and rubber build up on dry roads and float to the surface when rain first falls. Prolonged rain then washes it away, so the first few minutes are the worst.
Source: NHTSA wet weather driving guidance
What are the other warning signs?
All 55 warning signs on one page, or every US road sign by shape and color.
Test yourself on this sign and the rest of the set with a road signs practice test for Florida, Texas or California.
The artwork is the federal design itself, which the manual dedicates to the public domain in MUTCD 11th Edition, Part 1, Section 1D.06, checked 2026-09-09. The Interstate Shield, the 511 pictograph and the National Scenic Byway graphic are named exceptions and are not reproduced anywhere on this site.
Source: Manual on Uniform Traffic Control Devices, 11th Edition. Not affiliated with or endorsed by the Federal Highway Administration or any state agency.