This is a method to get variables to be global in Unreal.
First make a Blueprint of type GameInstance.
You need to set your level to use this game instance in Project Settings /Maps and Modes/ Game Instance/ Game Instance Class to <YourGameInstance>
Then open the game instance up and add some variables.
To access these variables to either get or set them, in another blueprint you need to Get Game Instance and then Cast To <YourGameInstanceName> (mine is called WeatherComntrol.)
Pulling a wire from the Blue output dot you should see under Variables/Default <Your VariableNames> that you can either get or set.