A method of operating a memory device to read data may include determining, in a first read interval associated with a first read operation, a threshold voltage distribution of a most significant program state of a target logical memory page included in a first physical memory page among a plurality of physical memory pages, the first read operation being an operation of reading the target logical memory page of the first physical memory page; transmitting, to a memory controller, a distribution determination result, the distribution determination result being related to the threshold voltage distribution; receiving, from the memory controller, offset levels corrected based on the distribution determination result; and adjusting a read voltage based on offset levels prior to performing a second read operation on a second physical memory page among the plurality of physical memory pages.