in order to have a more realistic storm system in AJE: HAN*, i have made this mod and i have already tested it a bit.
Here are the characteristics:
nearly all sea regions** are now subject to have storms and not only a few and always the same in vanilla.
So, expect to be surprised, there will be many more storms all round the map and their occurrences is highly unpredictable.
- Winters storms (december, january, february: yes, there are 3 winter months left) are less lethal than in vanilla.
However, avoid any fleet movement during winter or on very short distance if you don't want to lose your ships (3 storms hitting your fleet are enough to destroy it completely and the troops on board with

-Spring/Fall storms (march, april, september, october, november) are much less lethal than in vanilla and there are less than in winter.
However, a long trip could still be risky. Prefer short or medium trip.
- Summers storms (may, june, july, august) could rather being considered like an additionnal attrition for your ships and troops on board and don't represent a real threat (they are quite rare) except if you make a very, very long trip or if you are very, very unlucky.

So, to be short, remenber that there is always a risk for your ships and troops when you go on sea and this risk is directly proportional to the distance travelled and is season dependant.
This mod has been made with 1.01 beta patch for AJE: HAN.
In order to install it, unzip files and copy-paste it in your HAN subdirectory.
0.1 version:
[ATTACH]31788[/ATTACH]
Any feedbacks is welcome.
PS: i don't recommand to use this mod if you are playing against AI because AI is unable to understand that moving fleets on long distance during winter is a very, very bad idea.
* It should be also available for AJE: BOR but not for AJE.
** They are some exceptions like most coastal african sea regions.