Hi Josu,
This website will give you some insight into conditions over the March/April timeframe. It's pretty basic but, gives you a general overview month to month...
https://www.australia.com/en/facts-a...in-darwin.html
Obviously nothing is guaranteed but, at the bottom it gives you average temps & rainfall for each month. You will note that March is still quite wet but, April is considerably less so, based on averages.
Hopefully this might assist you; your contact will likely be able to provide you with more precise information.
Cheers