I guess you could make duplicate tiles. For Example, Create 2 CPU usage tiles, set one for a summer time frame from Month X to Month X, then do the same for the other tile and choose the winter months. You can set these time frames to adhere to specific tiles and you can also rename them to "CPU in the Summer" and "CPU in the winter"
Time desplayed in dynatrace GUI depends of time on your machine. Dynatrace is saving everything in GMT 0 timezone. Then time is changed depends of timezone of your workstation while preparing view for you.