A method, apparatus, and computer program product are provided for detecting changes in road traffic conditions based on vehicle probe data. Methods may include: receiving a plurality of probe data points; map-matching probe data points of the plurality of probe apparatuses to road segments of a candidate road of a road networks; for a plurality of time epochs, cluster probe speeds map-matched to road segments of the candidate road according to a clustering algorithm; establishing centroid speeds corresponding to clusters of probe speeds; spatially grouping said road segments according to probe-to-cluster mapping; and providing a road traffic condition change message in response to a difference between centroid speeds along the candidate road exceeding a predefined threshold, where the road traffic condition change message includes at least information about said road segment groups that correspond to said clusters.