Abbreviations and Codes Used in the Observer’s Diary

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While the notation has varied over the centuries, a standard for meteorological abbreviations and codes used in the observer’s diary has been slowly established. Below are tables with modern versions of such codes, which can help you better understand the comments accompanying the daily measurements.

Table 1: Code for wind direction

All directions are from true (not magnetic) North. When the wind is calm, enter 00 for direction.

COMPASS POINT (from which the wind is blowing)	CODED ENTRY
North	36
North-north-east	02
North-east	05
East-north-east	07
East	09
East-south-east	11
South-east	14
South-south-east	16
South	18
South-south-west	20
South-west	23
West-south-west	25
West	27
West-north-west	29
North-west	32
North-north-west	34

Table 2: Code for wind speed

Specification	Beaufort Force	Coded Entry (equivalent speed at 10 m in knots)
Calm: smoke rises vertically	0	00
Light air: direction of wind shown by smoke drift but not by wind vanes	1	02
Light breeze: wind felt on face; leaves rustle; ordinary vane moved by wind	2	05
Gentle breeze: leaves and small twigs in constant motion; wind extends light flag	3	09
Moderate breeze: raises dust and loose paper; small branches are moved	4	13
Fresh breeze: small trees in leaf begin to sway; crested wavelets form on inland waters	5	19
Strong breeze: large branches in motion; umbrellas used with difficulty	6	24
Near gale: whole trees in motion; inconvenience felt when walking against the wind (Force 7 is not regarded as a gale)	7	30
Gale: breaks twigs off trees; generally impedes progress	8	37
Strong gale: slight structural damage occurs (chimney pots and slates removed)	9	44
Storm: seldom experienced inland; trees uprooted; considerable structural damage occurs	10	52
Violent storm: very rarely experienced; accompanied by widespread damage	11	60
Hurricane: extremely rare; widespread damage and loss of life	12	68

Table 3: Present weather code and appropriate Beaufort letters or symbols

Even more detailed tables, with all of the associated symbols, can be found in this PDF file from the Met Office.

Miscellaneous phenomena
* must be occurring at the time of the observation
† must have occurred in the preceding hour
*† at the time of the observation OR in the preceding hour

Code	Description	Beaufort
Total Cloud:
0 - 2/8	clear sky	b
3/8 - 5/8	partly cloudy	bc
6/8 - 8/8	cloudy	c
8/8 total cloud	Uniform thick layer completely covering sky (overcast)	o

State of Sky:
01†	Clouds generally dissolving or becoming less developed
02†	State of sky generally unchanged
03†	Clouds generally forming or developing
04*	Visibility reduced by smoke (e.g. industrial smoke, forest fires)
05*	Haze	z
06*	Widespread dust in suspension in the air (NOT raised by wind) at or near station
07†	Dust or sand raised by the wind but no well developed dust- or sand-whirl(s), at or near station
08*†	Well developed dust- or sand-whirl(s) at or near station, but no dust- or sand-storm seen
09*†	Dust- or sand-storm within sight of the station	jkz
10*	Mist	m
*	Shallow fog (or ice fog) at station, not deeper than 2m. over land or 10m. over sea...	fs
11	... in patches
12	... more or less continuous
13	Lightning seen (but NO thunder heard)
*	Precipitation in sight (but not at station)...	jp
14	... NOT reaching the ground or surface of sea
15	... reaching the ground or surface of the sea, but at a distance of not less than about 3 miles
16	... reaching the ground or surface of the sea near to (but not at) the station
17*	Thunderstorm WITHOUT precipitation at the station	t
18*†	Squalls at or within sight of the station	q
19*†	Funnel cloud(s) (e.g. water-spout, tornado cloud) at or within sight of the station

Phenomena Ceased During Preceding Hour

Code	Description
20	Drizzle (not freezing) OR snow grains
21	Rain (not freezing)
22	Snow (in flakes)
23	Rain and snow (sleet) OR ice pellets
24	Freezing drizzle OR freezing rain
25	Shower(s) of rain
26	Shower(s) of snow (in flakes) OR of snow and rain (sleet)
27	Shower(s) of hail, small hail OR of rain and hail
28	Fog (or ice fog), i.e., visibility LESS THAN 1000m due to water particles or ice crystals
29	Thunderstorm (with OR without precipitation)

SAND or DUST STORMS

Code	Description	Beaufort
	Slight...	kzₒ
	...or Moderate:	kz
30	has decreased in the past hour
31	no appreciable change
32	has begun or increased in the past hour
	Severe:	KZ
33	has decreased in the past hour
34	no appreciable change
35	has begun or increased in the past hour

DRIFTING or BLOWING SNOW

Code	Description	Beaufort
36	Slight...	↓ksₒ
	...or Moderate drifting snow, generally low	↓ks
37	Heavy drifting snow, generally low	↓KS
38	Slight...	↑ksₒ
	...or Moderate blowing snow, generally high	↑ks
39	Heavy blowing snow, generally high	↑KS

FOG (or ICE FOG)

Fog denotes visibility LESS THAN 1000m due predominantly to water droplets (or ice crystals).

The Beaufort letter for fog depends upon its density: 0 m – 199 m = F ; 200 m -999 m = f

Code	Description	Beaufort
40	Fog at a distance (not at station in past hour)	jf
41	Fog in patches	if
	Fog has become THINNER in past hour:	F or f
42	sky/clouds discernible
43	sky/clouds obscured
	No appreciable change in fog in preceding hour:	F or f
44	sky/clouds discernible
45	sky/clouds obscured
	Fog has formed or become THICKER in preceding hour:	F or f
46	sky/clouds discernible
47	sky/clouds obscured
	FOG DEPOSITING RIME:
48	sky/clouds discernible
49	sky/clouds obscured

Precipitation from stratiform clouds

Code	Description	Beaufort
DRIZZLE
	Slight
50	intermittent	idₒ
51	continuous	dₒdₒ
	Moderate
52	intermittent	id
53	continuous	dd
	Heavy
54	intermittent	iD
55	continuous	DD
FREEZING DRIZZLE
56	slight
57	moderate
DRIZZLE with RAIN
58	slight	dₒrₒ
59	moderate...	dr
	...or heavy	DR
RAIN
	Slight
60	intermittent	irₒ
61	continuous	rₒrₒ
	Moderate
62	intermittent	ir
63	continuous	rr
	Heavy
64	intermittent	iR
65	continuous	RR
FREEZING RAIN
66	slight
67	moderate or heavy
RAIN (or drizzle) WITH SNOW (SLEET)
68
69	slight	rₒsₒ or dₒsₒ
SNOW (FLAKES)	moderate...	rs or ds
	...or heavy	RS or DS
	Slight
70	intermittent	isₒ
71	continuous	sₒsₒ
	Moderate
72	intermittent	is
73	continuous	ss
	Heavy
74	intermittent	iS
75	continuous	SS
SNOW GRAINS, ICE PELLETS etc.
76	Ice prisms
77	Snow grains	sh
78	Isolated star-like snow crystals
79	Ice pellets

Precipitation from cumuliform clouds only
† The intensity refers to thundery conditions not to the precipitation
* Hail here includes hail, small hail and snow pellets

Code	Description	Beaufort
SHOWERS...
...of RAIN
80	slight	prₒ
81	moderate...	pr
	...or heavy	PR
82	violent	PR
...of RAIN and SNOW (SLEET)
83	slight	prₒsₒ
84	moderate...	prs
	...or heavy	PRS
...of SNOW (FLAKES)
85	slight	psₒ
86	moderate...	ps
	...or heavy	PS
...of SNOW PELLETS, or SMALL HAIL with or without rain or sleet
87	slight
88	moderate or heavy
	of HAIL with or without rain or sleet
89	slight	phₒ
90	moderate...	ph
	...or heavy	PH
THUNDERY CONDITIONS:
	A thunderstorm without any precipitation is reported by code figure 17
Thunderstorm CEASED in past hour: PRECIPITATION CONTINUING
91	slight rain
92	moderate/heavy rain
93	slight snow/sleet/hail
94	moderate/heavy snow/sleet/hail
THUNDERSTORM WITH PRECIPITATION both at time of observation
	†Thunderstorm with ...
95	rain and/or snow (flakes), slight...	tlrₒ(sₒ)
	...or moderate	tlr(s)
96	hail*, slight...	tlhₒ
	..or moderate	tlh
97	rain and/or snow (flakes), heavy	TLR(S)
98	dust- or sand-storm	tlkz
99	hail*, heavy	TLH

Table 4: Code for observing and reporting visibility

The viewpoint for most objects is inside the Met Enclosure by the Stevenson screen (or the nearest location from which the object is visible) unless otherwise specified. Objects marked with asterisk (*) are not visible from the ground and may require a higher vantage point.

Coded Entry	General Description	Visibility Range (inclusive)	Standard Distance	Actual Distance	Name of Object	Bearing
X	DENSE FOG	0 - 24 yards / 0 - 19 metres
E	DENSE FOG	25 - 44 yd / 20 - 39 m	22 yd / 20 m	22 yd / 20 m	Calver Dome	NE
0	THICK FOG	45 - 104 yd / 40 - 99 m	44 yd / 40 m	38 yd / 35 m	Robinson Memorial Dome	NNW
1	THICK FOG	105 - 210 yd / 100 - 199 m	110 yd / 100 m	76 yd / 69 m	Observatory (Troughton) Dome	NNW
2	FOG	220 - 430 yd / 200 - 399 m	220 yd / 200 m	219 yd / 200 m	Hypercube (Viewpoint: Stone Calendar)	NW
3	MODERATE FOG	440 - 1090 yd / 400 - 999 m	440 yd / 400 m	443 yd / 405 m; 666 yd / 609 m; 728 yd / 666 m;	St Mark's Church Tower; Catholic Cathedral; Church of Ireland Cathedral	SE; W; SW
FOG LIMIT
4	VERY POOR VISIBILITY	1100 - 2190 yd / 1000 - 1999 m	1100 yd / 1000 m	830 yd / 760 m; 902 yd / 825 m	Police Station Radio Mast; Armagh City Hotel	S; SSW
5	POOR VISIBILITY	2200 - 4390 yards / 2000 - 3999 metres	2200 yd / 2000 m	1870 yd / 1710 m	Armagh DAB Radio Mast*	SW
6	MODERATE VISIBILITY	3 - 6 miles / 4 - 9 kilometres	2.5 mi / 4 km; 4.7 mi / 7 km	n/a; 4.3 mi / 6.9 km	n/a; Vicar's Cairn*	n/a; SSW
7	GOOD VISIBILITY	7 - 12 mi / 10 - 19 km	6.25 mi / 10 km	8.6 mi / 13.8 km	Carrigatuke Hill	SSE
8	VERY GOOD VISIBILITY	13 - 24 mi / 20 - 39 km	12.5 mi / 20 km; 18.7 mi / 30 km	12.1 mi / 19.4 km; 18.3 mi / 29.4 km	Mullyash Mountain; Slieve Gullion	SSE; SSW
9	EXCELLENT VISIBILITY	25 miles or over / 40 kilometres or over	25 mi / 40 km	n/a	n/a	n/a

Table 5: Code for state of ground

WITHOUT SNOW OR ICE	CODED ENTRY	WITH SNOW OR ICE
Surface of ground dry (without cracks and no appreciable amount of dust or loose sand)	0	Ground predominantly covered by ice
Surface of ground moist	1	Compact or wet snow (with or without ice) covering less than one-half of the ground
Surface of ground wet (standing water in small or large pools on surface)	2	Compact or wet snow (with or without ice) covering at least one-half of the ground but ground not completely covered
Ground flooded	3	Even layer of compact or wet snow covering ground completely
Surface of ground frozen	4	Uneven layer of compact or wet snow covering ground completely
Glaze on ground	5	Loose dry snow covering less than one-half of the ground
Loose dry dust or sand not covering ground completely	6	Loose dry snow covering at least one-half of the ground (but not completely)
Thin layer of loose dry dust or sand covering the ground completely	7	Even layer of loose dry snow covering ground completely
Moderate or thick cover of loose dry dust or sand covering ground completely	8	Uneven layer of loose dry snow covering ground completely
Extremely dry with cracks	9	Snow covering ground completely; deep drifts