Blueprint comunication/global variable for season change?

Thank you very much! You’ve set my mind in the right direction!
I was able to set my own tick function in editor, but I ended up using for loop and get all actors of class to change them wit single custom event - as I only need the instant switch solution. We use this for a live background in a movie shoot.
I still have to check it against large number of trees, but our landscape is not very large, and I can wait a bit for a loop to execute, no problem.

Later on I will be working on gradual change of seasons for a few timelapse shots, but this time using sequencer, so it should be fairly easy for me to animate the parameters.