I start patrol at 1 Jan 1940. Before that used random weather option in generator, set patrol month January, mediterrean was unchecked.
When patrol start I have clear sky, none parcipitations, none fog, wind 5m/s dir 131. I also started a couple of patrols in the same options and time and weather was the same in one difference of wind direction.
I tried user definied weather option too. I set wind dir N, speed calm, clouds partial, none rain and none fog and got the same weather as described above.
as mentioned above everything in generator was ok, files were updated but in game wather is perfect