Slippery When Wet Sign: Meaning and How to Drive

The slippery when wet sign is a yellow diamond with a black border and a black symbol of a car with skid marks. Its federal MUTCD code is W8-5, and it warns that the road ahead may be slippery when wet. The driving steps below come from three state handbooks, which are cited by state.

What the slippery when wet sign looks like

The federal Manual on Uniform Traffic Control Devices (MUTCD) names the sign W8-5, Slippery When Wet. Warning signs are diamond-shaped, with a black legend and border on a yellow background (Section 2C.02, p. 147).

The W8-5 symbol shows a car with skid marks (Figure 2C-7, p. 174). The MUTCD lists minimum sizes of 30x30 for single-lane roads, 36x36 for multilane roads, and 48x48 for freeways (Table 2C-1, p. 149).

What the sign warns about and when it is used

Section 2C.30 describes W8-5 as an optional sign for unexpected slippery conditions (p. 175). Under the MUTCD, warning signs are used based on an engineering study or engineering judgment, and they should be removed when the condition no longer exists (Section 2C.01, p. 147).

The MUTCD guidance says to place W8-5 in advance of the affected section and repeat it at intervals (Section 2C.30, p. 175).

Plaques that go with the sign

The MUTCD allows supplemental plaques reading ICE, WHEN WET, STEEL DECK, or EXCESS OIL to be used with W8-5 (Section 2C.30, p. 175). Plaques must share the warning sign's colors and be mounted below it (Sections 2C.57 to 2C.58, p. 195).

Related signs to know

W8-13, Bridge Ices Before Road, is a separate warning sign in the MUTCD. Section 2C.30 (p. 175) says it may be removed seasonally. Bridge ice is a different hazard from wet pavement, so check the words and symbol on the sign before you react.

The 2009 MUTCD numbered this section 2C.32, so older materials may cite that number.

What the state handbooks say

The statements below apply only to the state named in each item. Other states should check their own DMV handbook.

• Florida: The Florida handbook calls this warning sign "Slippery Surface" rather than "Slippery When Wet" (PDF p. 58, printed p. 50). It says to drive slowly in wet weather, not to speed up or brake quickly, and to make slow turns. It also says roads become slick during rainstorms and that wet roads increase braking distance (PDF p. 80). Source: Florida Driver Handbook
• Texas: The Texas handbook's warning-sign table says the wet-road sign means to slow down, and not to suddenly turn, speed up, or stop (PDF p. 33, printed p. 27). It says grooved pavement reduces slippery pavement in wet weather and that motorcyclists should use caution (PDF p. 35, printed p. 29). For bridge ice, it says the warning is displayed during winter and drivers should slow down and avoid sudden braking (PDF p. 34, printed p. 28). Source: Texas DL-7 driver handbook
• California: The California handbook lists Slippery When Wet among warning signs (PDF p. 43, printed p. 37). On wet roads, it says to reduce speed by 5 to 10 mph and allow more space between vehicles (PDF p. 67, printed p. 61). It also says some surfaces are more slippery when wet and usually have warning signs posted, and that drivers should slow down at the first sign of rain because oil and dust build up during dry, hot periods (PDF p. 67, printed p. 61). Source: California Driver Handbook

What to do when you see the sign

The federal notes cover the sign's design, size, and placement. The driving steps above come from the state handbooks, so use the handbook for your own state. If you are studying for your permit, GetMyPermit's practice test offers practice tests for every state.

Sources

• MUTCD Chapter 2C, 11th Edition
• MUTCD 2009 Edition, Part 2C
• Florida Driver Handbook
• Texas DL-7 Driver Handbook
• California Driver Handbook