German WWII Naval Wind Forecast Code - "Windschlüssel für Deutsche Seeschiffe"

This is a German Navy code for transmitting wind information in weather forecasts to ships at sea.
The code was aquired by the C-bureau (C-byrån), the WWII Swedish espionage organisation, and then passed on to FRA.

Cover sheet & Page 1 of the code

The cover sheet says in Swedish that this is a SECRET Report from Germany containing a weather code of the German Navy editions eighteen and nineteen.
Below is added, in longhand, Handed over to FRA from dept. M, May 14th, 1945. and Hand over to Head of bureau B after copying [...].

The page in German has a typed legend on top saying, in Swedish, that this document belongs to report(?) 824 of November 13th, 1944. Then it says, in German:
No. 929, SECRET, Wind crypto for German ships at sea, booklet 1 (for receiving radio stations) (19th edition), Part 4 of the Secret Weather and Sea cryptographic proceedures of the Navy. Main Command of the Navy, Berlin 1944.
Scan of cover leaflet Scan of Kriegsmarine Code

Message example & Daily key indicating chart

These scans of a message example (left), and chart indicating daily keys, translate as follows.

E. Example
The following High Sea Radio Station report is received on October 5th. According to the chart of daily keys for October 1944, the key numbered 8 is to be used for decoding. With the help of this key, the receiver decodes the wind forecast.

High Sea Radio Station Report. Decodes to the following indicating letters when using key number 8. Area and wind forecast according to chart K.

854 l North-easterly winds

212 k Åland archipelago, Bay of Finland and Bay of Bothnia

006 w Increasing wind

701 q Wind strength 4 - 5

... ... ...

Table "T"

Valid Key Tables according to Date

(Keys to change daily at 0500 hours German Standard Time.)

October 1944.

Day of month:

10.

11.

12.

13.

14.

15.

Valid key tables:

...

Daily key "4"

Daily key number 4 - receiving part:
Scan of Kriegsmarine Code

Tafel "K"

Tafel "K", or Chart "K" gives the meaning of the letters you get when decoding the received three figure code groups with the daily key. Letters a through k give the area where the forecast is valid. The code was used for two such areas, Area I being the North Sea and the Baltic, Area II beginning in northern Skagerrak following the Norwegian coast up to the polar region. In Area I, the letters e and f indicate the coastal waters of Denmark, for instance.
The letters l through z give wind directions, speeds, and tendencies.

Table "K"
Sea area indicators and Wind forecast code letters.
Indicator	Sea area	Code Letter	Wind forecast
	I. Sea areas in the North Sea and Baltic.	l	North-easterly
a/b	Hoofden	m	South-easterly
c/d	German Bight	n	South-westerly
e/f	Danish coastal waters	o	North-westerly
g/h	Western Baltic and Pomeranian Bight	p	Strength 0-3
i	Eastern Baltic	q	Strength 4-5
j	Northern Baltic	r	Strength 6-7
k	Åland archipelago, Bay of Finland and Bay of Bothnia	s	Strength 8-10
	II. Sea areas from northern Skagerrak upto Arctic coastal waters.	t	Strength 11-12
		u	No changes
		v	Decreasing
a/b/c	Northern Skagerrak	w	Increasing
d/e	Norwegian western coast
f/g	Norwegian northern coast	x	Changing wind
h/i	Lofoten	y	Veering left
j/k	Arctic coastal waters	z	Veering right

Back to index page

High Sea Radio Station Report.	*Decodes to the following indicating letters* when using key number 8.**	Area and wind forecast according to chart K.
854	l	North-easterly winds
212	k	Åland archipelago, Bay of Finland and Bay of Bothnia
006	w	Increasing wind
701	q	Wind strength 4 - 5
...	...	...