The technological advancements in service oriented architectures have given rise to Cloud computing as a new platform in the area of distributed computing. Virtualization is a prominent technology adopted by cloud while providing pay as per usage model. Cloud provides the computing resources in terms of different type of virtual machines. VM migration is a fundamental phenomena in cloud systems while providing uninterrupted service and load balancing to its users according to service level agreement. The virtualization and migration poses many challenges and complexities because of many uncertainties. Uncertainties are the inaccurate data in the form of task parameters, variation in the VM performance etc. As the Fuzzy logic can be employed effectively in decision making with inaccurate data we propose fuzzy logic based real time scheduling algorithm to deal with the uncertainties. The proposed algorithm in this paper performs in a better way in meeting of deadlines of real time workflows under uncertain data and VM migrations.