There is a at the top center of the screen in Day, Week, and Agenda view. It allows you to open the Month view calendar at the top of the screen and another calendar view at the bottom. Simply drag the calendar handle all the way down the screen to open the month calendar above the currently selected calendar type. Drag it all the way back up to close it.
You can also view a single week of the Month view. Drag the handle slightly downward if the Month view is hidden or, when it’s open, stop the upward drag motion before you reach the top. While viewing a single week in the Month view, you can swipe up or down to display the previous or next week. Swipe the left or right to view previous or subsequent months.