In early April 2022, I was driving a car on a German motorway somewhere near the border between Hessen and Rheinland-Pfalz. The local speed limit was 100 km/h, with an additional speed limit 80 km/h bei Nässe (literally: „by wetness“), meaning when there is a layer of water on the road. It was freezing and lightly snowing at the time, but the snow did not stick to the road. I was driving around 95 km/h (like everybody else) and, when passing a static radar speed gun, saw a white flash indicative of a photograph being taken, suggesting I may have passed a speed limit and might expect a fine.

I was surprised, because air and road weren't wet; it was snowing, and I don't think snow is wet. Does traffic law enforcement consider snow as wet? There is a long discussion on this forum at verkehrsportal.de, but it seems everyone is speculating and nobody knows the answer.

During a charging break soon after the photograph was taken, I noticed that my front license plate was obscured by snow (so were all others), for which there is apparently a €5 fine — so perhaps the flash was not due to speeding but due to an obscured license plate (they can probably still tell the car through the Umweltplakat). So far, I have not received any letter for any fine.

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    If the snow didn't stick top the ground, presumably it was melting, and making the ground wet. Commented Apr 28, 2022 at 8:31
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    A road with water and/or ice on it, at a temperature near freezing, is likely to be slicker than one that is considerably above or below freezing. If the criteria for "wet" don't take this fact into account, it would seem to defeat the purpose of having a lower speed limit for wet conditions. (That is, a wet road at 10°C is probably less dangerous than a road with melting snow on it at 1°C or 0°C.)
    – phoog
    Commented Apr 28, 2022 at 9:00
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    @Dirty-flow I wonder if/how they monitor the state of the road to decide whether to flash at drivers passing by…
    – gerrit
    Commented Apr 28, 2022 at 10:38
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    @phoog I believe the motivation for the lower speed limit is about aqua-planing, not about slippery surfaces.
    – gerrit
    Commented Apr 28, 2022 at 10:40
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    @gerrit how could a road covered in wet snow not itself be wet?
    – phoog
    Commented Apr 28, 2022 at 22:04

1 Answer 1


Wetness does not comprise all kinds of precipitation.

  • There are separate signs for snowfall (268), for black ice (1007‑30, 101‑51), for fog (1007‑61), smoke (1007‑31), and for “wetness” (1053‑35). The legislation therefore distinguishes between those states.
  • The entire street needs be covered by a layer of liquid water. Puddles or other patches of wetness do not matter. (German Federal supreme court decision of 1977‑12‑20, 4 StR 560/77)
  • The road condition must be recognizable from the driver’s seat. Either it’s currently raining so the windshield is covered by (liquid) water, or there are other indications of the previously mentioned criterion.

I don’t think the speed traps are “smart” enough to determine partially obscured license plates or even wetness. The electric circuits simply measure the speed of any moving object in front of them and exceeding the limit releases the shutter. There’s usually an orange color filter in front of the flashlight so it doesn’t dazzle drivers (at night).

  • Great answer! Could you add some sources? Are there traffic signs for explicitly lower speed limits in case of snowfall, black ice, or fog (apart from generic "drive safely" rules)?
    – gerrit
    Commented May 4, 2022 at 15:36
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    Germany’s traffic administration’s creativity is unlimited, yet (currently) “when wet” is the only conditional weather-related sign that can be combined with a posted speed limit. Commented May 4, 2022 at 19:42
  • “When wet” can actually be combined with any reasonable sign, apparently even with “slippery road” (sign 114) as I saw today. Well, duh! “Slippery when wet.” This is so German. To be fair, it was on a serpentine road. I also saw “no overtaking when wet” (sign 276). Commented Jul 15, 2022 at 19:52

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