The warning from the German Weather Service is clear. "In the morning (…) heavy gusts of wind in the north, in the North Sea area a storm situation arises with gale-force gusts or gusts of more than 105 km / h (Bft 11 to 12). There are heavy gusts of wind on the Baltic Sea coast Gusts not excluded."
In short, it will be more than uncomfortable. Anyone who is still at sea should head for a safe harbor as quickly as possible. And owners whose ships are in the ports in Niedersaschen, Bremen, Hamburg and Schleswig-Holstein in particular - there is a storm warning in the second highest category for these regions - should ensure that their boat is moored in a storm-proof manner. Yes, because otherwise you risk your insurance cover.

Official storm warning level 3 of the DWD for northern Germany
And not just hers. If you play it safe, you not only deploy double mooring lines and additional fenders on your own boat, but also take a look at the mooring lines and fenders of the neighboring boaters. Because if a ship breaks loose in a hurricane and its owner has not acted negligently, he or his insurance company does not have to be liable for damage that occurs to neighboring ships!
Many are not aware of this fact. Only those who have comprehensive insurance for their own ship are off the hook. When in doubt, all others are left with high repair costs.
If in doubt, ask the harbor master for help
If you don't have a chance to see your ship in time, you should try to contact the harbor master and ask him to look after the lines. You may also know of owner friends who are near the port and can ask them to keep an eye on the ship for the next few hours.
Incidentally, in some ports there is not only danger from the wind - in some places the water level could fall rapidly due to storms. Therefore, make sure in any case in the affected ports that there is enough water under the keel even in an extreme situation. If in doubt, move the ship to a berth with greater water depth.
We have described in detail in a YACHT article how to secure your ship from storms. We provide the article here for free download as a PDF.

YACHT article about mooring a boat in the harbor in a more themed way