Hmmm. Ok so it's not just me then.
After further testing of the problem I think I was able to reproduce the locked weather effect.
Most times I have to leave mid mission so I save and exit to continue another time. So it seems that saving the game mid mission is the culprit after all.
And this can, in a sense, be used as a cheat. I had sinced docked and started a new patrol then as usual had to leave the sim once more. Only this time the save was during Perfect conditions.
No fog, precip and wind was 5 kts.
And wouldn't you know it. when I returned the rest of the mission maintained this fine weather till I docked.
So it seems you can simply start a mission, wait for desired weather conditions. save, exit, restart. and it will hold untill you dock.
The only real way to eliminate this and maintain any randomness of the weather system is to start and complete a full mission in one sitting before exiting the Sim.
But it was neat to be able to actualy use up all the main gun ammo during one mission with the weather cheat prior to having to use the torps. Made for some great renown
I never sunk so many ships before
But I do look forward to SH4 and dynamic weather.
