EDIT: Solved, read below
Hi there!
I’m trying to retrieve a wind strength as a scalar in the visual effects node editor. Another viable alternative would be to get particle velocity as a scalar.
Unfortunately I can only get both as vector3 and there seems to be no way to calculate a vector length in the node editor. Have I missed something, and is it somehow possible? 
Thank you!
SOLUTION:
Used a simvar node and an AMBIENT WIND VELOCITY variable