Methods and systems are disclosed for participative sensing of road friction conditions by vehicles, collection of the friction data from a large number of vehicles by a central server, processing the data to classify friction conditions by roadway and locale, and sending notifications of the friction conditions to vehicles as appropriate. A large number of vehicles use participative sensing systems to identify road friction estimates which are reported to the central server—where the vehicles use sensor data and vehicle dynamic conditions to estimate friction. The central server stores and aggregates the friction data, filters it and ages it. Vehicles requesting advisories from the central server will receive notices of road friction conditions which may be significant based on their location and heading. Driver warnings can be issued for low friction conditions ahead, and automated vehicle systems may also respond to the notices.