There appears to be plenty of room for confusion in this thread.
First 80/20 is correct with respect to crosswind values in the AFM. The manufacturer publishes max demonstrated crosswinds for manual landings. Operators can apply for alleviation / interpretation from the authority, but I would not recommend pushing any demonstrated limit. All crosswind limits should be revised to lower values for wet / slippery runways as advised by the manufacture.
Autoland performance (certification) is a complex mixture of aircraft actual demonstrated landings and simulated landings – touchdown in the required box – narrower than the runway width. AFM statements vary by national authority; for some the autoland crosswind clearance is a hard limit (the JAA?), for others the value may only be the demonstrated value (the FAA?). Recently the major authorities met to harmonize the regulations and I suspect that hard limits now apply universally and are hidden in statements such as “ Limitations on the use of the system and crew procedures to be incorporated in the aeroplane Flight Manual;” from JAR AWO 309 (f).
My second point is that there is a hint of confusion between dual channel ILS ground installations; a must for actual conditions, and dual channel autopilot systems. I do not know if the 737 can autoland on a single autopilot channel (I doubt it, but I am prepared for education). Both channels of dual channel systems that I operated had to be operational so that in the event of a failure the auto pilot failed soft i.e. the aircraft was approximately in trim. I do not know of any autoland systems that are cleared for hard fail landings even during training. Further confusion and alternatives may exist with degraded triple or dual-dual autoland systems, but again I do not think that these apply to the 737. Also, additional crosswind limits may apply to those systems with ground rollout capability – defiantly not the 737.
Thus my advice follows wing737, revise your technical knowledge of the system, read the AFM, and stay with the published limits – hard or demonstrated.
Thus to answer the original question, the actual weather should not change the autoland crosswind limit (excluding ground roll out systems); the overriding factors are the autopilot capability and level of failure protection. A bit like some pilots?
30kts in Cat3? Unfortunately yes; fog at St Johns NF, and blowing snow at Keflavik. However without the appropriate takeoff limits for a slippery runway the conditions were observed from the comfort of the bar.