Why are the forecasted costs in my Billing and Cost Management console unexpectedly high?

Resolution

Most AWS services bill on demand, meaning that your overall bill steadily increases over the course of a month. However, some services or features bill a larger amount at one time, usually on or near the first of the month.

Your forecasted usage for the rest of the month might appear to be higher than you expect. This is because your average daily cost is higher at the beginning of the month. As the month progresses, the forecast shows a more accurate prediction of your final monthly bill.

Related information

How do I reduce my AWS bill?

What is AWS Billing?