This spring, several strikes are planned in France. The train service, and possibly also the planes, will be severely impacted. The strike days and information on the train services are updated regularly. The strike days, where the number of trains circulating will be considerably small, are already known. You can find information on the strike at SNCF here.
Concerning the planes, Air France already had some strike days early April but there is nothing announced for May. However, this situation may evolve.