Hey Leon,
I’ve been living in Darwin for 15 years, and like everywhere else the weather is increasingly unpredictable.
Below is a link to a paper about it from BOM which suggests Jan would be the best month.
http://www.bom.gov.au/climate/averag...explain_td.pdf
Anecdotally I would say that I agree. End of build up (November) can also be good. Feb is usually a bit too late, but I’ve noticed it’s getting wetter for longer and later.
The monsoons don’t bring a lot of lightening just a lot of rain and a well deserved drop in humidity.
Best place to look is out over the Arafura Sea. Lots of gorgeous places for that. Try the sailing club in Fannie Bay, best sunsets and storms. Along with some great food and a cold beer.