There will be lightning!
When scanning the net for examples on different weather effects I came across an amazing tutorial written by Michael Hoffman on how to make realistic looking light effects. This inspired me to write a very similar lightning engine.
The main difference between the solutions is that Michael's uses a pre-drawn image rendering the lightning bolts while mine uses the line strip drawing primitive. Michael's lightnings are more realistic looking than mine but since I'm going for more of a pixel-art looking aesthetic the line strip is a better choice for me.
Example of a lightning branch.
I began creating a single lightning bolt and then added feature after feature until I had a full blown lightning engine sending randomized bolts and branches through the sky. As with the rain engine this engine also has a lot of settings, some of these are:
Interval between lightning strikes
Min and max number of branches
This was quite fun to code and I'm quite pleased with the result. Things left to add is sound for thunder and maybe a flashing background.
Working with the lightning engine I also spent a few hours tinkering with HLSL and including shaders. It was really interesting and fun, but for now it will be a type of coding I will save for the polishing phase.
For anyone getting started with MonoGame and HSLS I highly recommend the article My First Pixel Shader(s).
I'd be very happy for recommendations on other good HSLS pages.