Tired of ending up in bad weather where you can't launch torpedos or shoot with the deck gun. Faults, premature detonations and that juicy tanker just sails away...
Why not check out the weather forecast before your patrol. It is entirely sensible that Uboat Kommandanten and BdU considered the weather in their planning.
https://app.metoceanview.com/hindcast/
On this site is a lot of solid weather data of the seas. I think the most interesting one is mean wave height. The weather patterns of the Atlantic today should not be that different from 1940. If you check out the months, you will see that North Atlantic region gets very red and high waves during winter time. So if your patrol is at such time, consider the Mediterranean, Arctic sea (very little daylight in the winter) or the South Atlantic. Return to the North Atlantic in spring.
Quick guide:
https://app.metoceanview.com/hindcast/
Global summary overlay: Mean significant wave height
Choose your patrol month