The amount of outbound data transfer, or data egress, can greatly affect Azure costs since there are charges for data that goes out of an Azure region to the internet or to other regions, after the free tier limit is reached. The type of storage account will often have a set price for capacity with known additional costs for operations and outbound transfers. Deploying resources across multiple regions may increase cost due to data egress fees but isn’t necessarily associated with unpredictable fluctuations unless the traffic volume varies significantly. Data retention periods would result in predictable increases in storage costs if the data increases over time but not unpredictable month-to-month changes.