good egg, first to reiterate some previous points. Crosswind ‘max demonstrated’ is in the Operating Manual as advisory information. The AFM contains limiting conditions as hard aircraft limits (rarely for manual landing, always for autoland).
Previously, aircraft manufacturers published advise according to what had been tested for manual landing, usually on an opportunity basis. This might only relate to dry runway, or steady wind. However with increasing focus on runway excursions, manufacturers might now provide expanded advice on interpreting gusts, wet or contaminated runways, width, etc.
The message is to read the small print in the manufacturers documents.
There are several safety publications with advise on wet crosswind restrictions, but the manufacturer should always be considered first. Then assess other factors as per landing distance, how wet is ‘wet’, what form of contamination, type of runway surface, width; all relate to crosswinds.
Wet smooth concrete may be like like ice. High-friction porous surfaces are generally good, providing that they are not contaminated with rubber or dust . Grooving should not be included in assessments unless you are sure that the grooves are clear and provide good drainage, which may not the case after a heavy downpour.
IMHO advice given re crosswind component should be treated as a limit, and further restriction applied for gusts, particularly as the actual variation is unknown; ATC reports are not absolute, wind not measured at the threshold, only an average, etc.
If you don’t know, not sure - how wet, what gust, width; give yourself more margin.
TA, #33, does the U.K. CAA agree with that view? IIRC there was a policy statement that there is no such thing as ‘damp grooved equals dry’?
Jw, #35, re landing distance; except when using credit for reverse to stop, and reverse affects directional control - fin blanking etc, or an aircraft type tends to lift a wing in crosswinds without sufficient aileron input.