Slitherine

German battleship on this screenshot is technically outside of any spotting range, why is it visible?

Was the port attacked by an air unit in the opponents turn? If a Strategic bomber has the range to the port, a SAC attack could be performed to see if any unit is present.

Sea Spotting of ground units is 2 hexes in fair weather and you've got a partisan there!

Port was not attacked and it's not fair weather.
Previous turn might be fair though, if it works this way.

Previous turn fair, Yes it works this way.

You learn something new every day, I though vision zones are recalculated for both sides at start of every Axis turn, when weather is rolled.
Well, thanks.

Spotting ranges are altered at the end of your turn. So when you start your turn you see the spotting of how it was at the end of the opponent's turn. So spotting actually lags behind a little from the dynamic spotting. If you move a unit then it will spot immediately after the movement.

There is logic in this because you use intelligence reports to guess where the enemy is. These reports quickly become old. Let's say you're in the beginning of October with mud weather. Then you use the intelligence from late September which had fair weather.

It's been like this since vanilla CEAW.