You are Here: Home » » Symbols & Code Figures

Weather Symbols & Code Figures

The code figures are used to transmit meteorological data in the SYNOP Code Form. The weather symbols are drawn on the Station Weather Plot to represent the meteorological data in the synop report.

Pressure Trend

WMO Code Table 0200

Symbolic Letter(s) a - characteristic of pressure tendency during the three hours ending at the time of the observation.

Code figures 0, 1, 3, 5, 6 and 8 are not used by an automatic weather station.

Code Figure	Description	Weather Symbol
0	Increasing then decreasing, atmospheric pressure the same or higher than three hours ago
1	Increasing then steady or increasing then increasing more slowly, atmospheric pressure now higher than three hours ago
2	Increasing steadily or unsteadily, atmospheric pressure now higher than three hours ago
3	Decreasing or steady then increasing or increasing then increasing more rapidly, atmospheric pressure now higher than three hours ago
4	Steady, atmospheric pressure the same as three hours ago
5	Decreasing then increasing, atmospheric pressure the same or lower than three hours ago
6	Decreasing then steady or decreasing then decreasing more slowly, atmospheric pressure now lower than three hours ago
7	Decreasing steadily or unsteadily, atmospheric pressure now lower than three hours ago
8	Steady or increasing then decreasing or decreasing then decreasing more rapidly, atmospheric pressure now lower than three hours ago

Top of page

High Level Cloud

WMO Code Table 0509

Symbolic Letter(s) C_H - clouds of genera cirrus, cirrocumulus and cirrostratus.

Code Figure	Description	Weather Symbol
0	No high level cloud
1	Cirrus in filaments or hooks not progressively invading the sky
2	Dense cirrus
3	Dense cirrus from cumulonimbus
4	Cirrus progressively invading the sky
5	Cirrostratus increasing but below 45° elevation
6	Cirrostratus increasing and above 45° elevation
7	Cirrostratus covering the whole sky
8	Cirrostratus neither progressively invading the sky nor entirely covering it
9	Cirrocumulus
/	High level cloud obscured for any reason

Top of page

Low Level Cloud

WMO Code Table 0513

Symbolic Letter(s) C_L - clouds of genera stratocumulus, stratus, cumulus and cumulonimbus.

Code Figure	Description	Weather Symbol
0	No low level cloud
1	Small cumulus
2	Cumulus of moderate or strong vertical development
3	Cumulonimbus without anvil
4	Stratocumulus from spreading out of cumulus
5	Stratocumulus not from the spreading of cumulus
6	Stratus
7	Stratus fractus and cumulus fractus of bad weather
8	Cumulus and stratocumulus at different heights
9	Cumulonimbus with anvil
/	Low level cloud obscured for any reason

Top of page

Middle Level Cloud

WMO Code Table 0515

Symbolic Letter(s) C_M - clouds of genera altocumulus, altostratus and nimbostratus.

Code Figure	Description	Weather Symbol
0	No middle level cloud
1	Thin altostratus
2	Thick altostratus or nimbostratus
3	Semitransparent altocumulus
4	Altocumulus continually changing shape — lenticular altocumulus
5	Altocumulus progressively invading the sky
6	Altocumulus from the spreading out of cumulus
7	Altocumulus at more than one level or thick altocumulus in a single layer
8	Altocumulus with tufts or sproutings
9	Altocumulus of a chaotic sky
/	Middle level cloud obscured for any reason

Top of page

Wind Direction

WMO Code Table 0877

Symbolic Letter(s) dd - true direction, in tens of degrees, from which wind is blowing.

Code Figure	Description
00	Calm
01	5° - 14°
02	15° - 24°
03	25° - 34°
04	35° - 44°
05	45° - 54°
06	55° - 64°
07	65° - 74°
08	75° - 84°
09	85° - 94°
10	95° - 104°
11	105° - 114°
12	115° - 124°
13	125° - 134°
14	135° - 144°
15	145° - 154°
16	155° - 164°
17	165° - 174°
18	175° - 184°
19	185° - 194°
20	195° - 204°
21	205° - 214°
22	215° - 224°
23	225° - 234°
24	235° - 244°
25	245° - 254°
26	255° - 264°
27	265° - 274°
28	275° - 284°
29	285° - 294°
30	295° - 304°
31	305° - 314°
32	315° - 324°
33	325° - 334°
34	335° - 344°
35	345° - 354°
36	355° - 4°

Top of page

Base of Lowest Cloud

WMO Code Table 1600

Symbolic Letter(s) h - height above surface of the base of the lowest cloud.

Code Figure	Description
0	0 to 50 m	(0 to 150 ft)
1	50 to 100 m	(150 to 300 ft)
2	100 to 200 m	(300 to 600 ft)
3	200 to 300 m	(600 to 1,000 ft)
4	300 to 600 m	(1,000 to 2,000 ft)
5	600 to 1,000 m	(2,000 to 3,000 ft)
6	1,000 to 1,500 m	(3,000 to 5,000 ft)
7	1,500 to 2,000 m	(5,000 to 6,500 ft)
8	2,000 to 2,500 m	(6,500 to 8,000 ft)
9	2,500 m or more, or no cloud
/	Height unknown due to sky obscured

Top of page

Inclusion of Precipitation Data

WMO Code Table 1819

Symbolic Letter(s) i_R - indicator for inclusion or omission of precipitation data.

Code Figure	Description
0	Reported in Sections 1 and 3
1	Reported in Section 1
2	Reported in Section 3
3	Not reported in Sections 1 and 3, amount = 0
4	Not reported in Sections 1 and 3, amount not available

Top of page

Source and Units of Wind Speed

WMO Code Table 1855

Symbolic Letter(s) i_W - indicator for source and units of wind speed.

Code Figure	Description
0	Wind speed estimated in metres per second
1	Wind speed from anemometer in metres per second
3	Wind speed estimated in knots
4	Wind speed from anemometer in knots

Top of page

Inclusion of Present and Past Weather

WMO Code Table 1860

Symbolic Letter(s) i_x - indicator for type of station operation and for present and past weather data.

Code Figure	Station Operation	Description
1	Manned	Past and present weather included
2	Manned	Past and present weather omitted, no significant weather to report
3	Manned	Past and present weather omitted, data not available
4	Automatic	Past and present weather included, using Code Tables 4677 and 4561
5	Automatic	Past and present weather omitted, no significant weather to report
6	Automatic	Past and present weather omitted, data not available
7	Automatic	Past and present weather included, using Code Tables 4680 and 4531

Top of page

Amount of Cloud

WMO Code Table 2700

Symbolic Letter(s) N and N_h - total cloud cover & amount of lowest cloud.

The station circle is at the centre of the station plot and is represented by the symbol for total cloud cover. All other symbols and data are plotted around the station circle.

Code Figure	Description	Weather Symbol
0	No cloud
1	1 okta (eighth) of cloud or less, but not zero
2	2 oktas of cloud
3	3 oktas of cloud
4	4 oktas of cloud (half the sky covered)
5	5 oktas of cloud
6	6 oktas of cloud
7	7 oktas of cloud
8	8 oktas of cloud (sky completely covered)
9	Sky obscured
/	No observation made

Top of page

Rainfall

WMO Code Table 3590

Symbolic Letter(s) RRR - amount of precipitation that has fallen during the period preceding the time of observation, as indicated by t_R.

Rainfall of 1 mm or more is rounded to the nearest whole number.

Code Figure	Description
000	no precipitation
990	trace
991	0.1 mm
992	0.2 mm
993	0.3 mm
994	0.4 mm
995	0.5 mm
996	0.6 mm
997	0.7 mm
998	0.8 mm
999	0.9 mm
001	1 mm
002	2 mm
etc	etc
988	988 mm
989	989 mm or more
///	precipitation not measured

Top of page

Sign of Temperature

WMO Code Table 3845

Symbolic Letter(s) s_n - indicator for sign of temperature.

Code Figure	Description
0	Positive or zero
1	Negative

Top of page

Rainfall Period

WMO Code Table 4019

Symbolic Letter(s) t_R - duration of period of reference for amount of precipitation, ending at the time of the report.

Code Figure	Description
1	Total precipitation during the 6 hours preceding the observation
2	Total precipitation during the 12 hours preceding the observation
3	Total precipitation during the 18 hours preceding the observation
4	Total precipitation during the 24 hours preceding the observation
5	Total precipitation during the 1 hour preceding the observation
6	Total precipitation during the 2 hours preceding the observation
7	Total precipitation during the 3 hours preceding the observation
8	Total precipitation during the 9 hours preceding the observation
9	Total precipitation during the 15 hours preceding the observation

Top of page

Horizontal Visibility

WMO Code Table 4377

Symbolic Letter(s) VV - horizontal visibility at surface.

Code Figure	Description
00	< 0.1 km
01 to 50	0.1 to 5.0 km, in increments of 0.1 km
56 to 80	6 to 30 km, in increments of 1 km
81 to 88	35 to 70 km, in increments of 5 km
89	> 70 km

Top of page

Past Weather

WMO Code Table 4531

Symbolic Letter(s) W_a1W_a2 - past weather reported from an automatic weather station.

Only the code figure appropriate for our local operations is shown. Thunderstorms in the past hour but not at the time of observation are reported as present weather.

Code Figure	Description	Weather Symbol
4	Precipitation with no other information available

WMO Code Table 4561

Symbolic Letter(s) W₁W₂ - past weather reported from a manned weather station, or a manned report of past weather from an automatic weather station.

Code Figure	Description	Weather Symbol
0	Cloud covering 1/2 or less of the sky throughout the appropriate period
1	Cloud covering more than 1/2 of the sky during part of the appropriate period and covering 1/2 or less during part of the period
2	Cloud covering more than 1/2 of the sky throughout the appropriate period
3	Sandstorm, duststorm or blowing snow
4	Fog or ice fog or thick haze
5	Drizzle
6	Rain
7	Snow, or rain and snow mixed
8	Shower(s)
9	Thunderstorm(s) with or without precipitation

Top of page

Present Weather

WMO Code Table 4680

Symbolic Letter(s) w_aw_a - present weather reported from an automatic weather station.

Only the code figures appropriate for our local operations are shown.

Code Figure	Description	Weather Symbol
12	Distant lightning
26	Thunderstorm (with or without precipitation) during the preceding hour but not at the time of the observation
90	Thunderstorm at the time of the observation but no other information available

WMO Code Table 4677

Symbolic Letter(s) ww - present weather reported from a manned weather station, or manned report of present weather from an automatic weather station..

Code Figure	Description	Weather Symbol
00 - 19	No precipitation, fog, ice-fog (except for 11 and 12), duststorm, sandstorm, drifting or blowing snow at the station at the time of observation or during the preceding hour (except 09 and 17)
00	Cloud development not observed or not observable
01	Clouds generally dissolving or becoming less developed
02	State of sky on the whole unchanged
03	Clouds generally forming or developing
04	Visibility reduced by smoke, e.g. grassland or forest fires, industrial smoke or volcanic ashes
05	Haze
06	Widespread dust in suspension in the air, not raised by wind at or near the station at the time of observation
07	Dust or sand raised by wind at or near the station at the time of observation, but no well developed dust whirl(s) or sand whirl(s), and no duststorm or sandstorm seen
08	Well-developed dust whirl(s) or sand whirl(s) seen at or near the station during the preceding hour or at the time of observation, but no duststorm or sandstorm
09	Duststorm or sandstorm within sight at the time of observation, or at the station during the preceding hour
10	Mist
11	Patches of shallow fog or ice fog at the station, not deeper than about 2 metres
12	More or less continuous shallow fog or ice fog at the station, not deeper than about 2 metres
13	Lightning visible, no thunder heard
14	Precipitation within sight, not reaching the ground
15	Precipitation within sight and reaching the ground, but estimated to be more than 5 km from the station
16	Precipitation within sight and reaching the ground, near to, but not at the station
17	Thunderstorm, but no precipitation at the time of observation
18	Squalls at or within sight of the station during the preceding hour or at the time of observation
19	Funnel cloud(s) at or within sight of the station during the preceding hour or at the time of observation
20 - 29	Precipitation, fog, ice-fog or thunderstorm at the station during the preceding hour but not at the time of observation
20	Drizzle (not freezing) or snow grains during the preceding hour but not at the time of observation
21	Rain (not freezing) during the preceding hour but not at the time of observation
22	Snow during the preceding hour but not at the time of observation
23	Rain and snow or ice pellets during the preceding hour but not at the time of observation
24	Freezing drizzle or freezing rain during the preceding hour but not at the time of observation
25	Shower(s) of rain during the preceding hour but not at the time of observation
26	Shower(s) of snow, or of rain and snow during the preceding hour but not at the time of observation
27	Shower(s) of hail or of rain and hail during the preceding hour but not at the time of observation
28	Fog or ice fog during the preceding hour but not at the time of observation
29	Thunderstorm (with or without precipitation) during the preceding hour but not at the time of observation
30 - 39	Duststorm, sandstorm, drifting or blowing snow
30	Slight or moderate duststorm or sandstorm - has decreased during the preceding hour
31	Slight or moderate duststorm or sandstorm – no appreciable change during the preceding hour
32	Slight or moderate duststorm or sandstorm - has begun or has increased during the preceding hour
33	Severe duststorm or sandstorm - has decreased during the preceding hour
34	Severe duststorm or sandstorm – no appreciable change during the preceding hour
35	Severe duststorm or sandstorm - has begun or has increased during the preceding hour
36	Slight or moderate drifting snow, generally below eye level
37	Heavy drifting snow, generally below eye level
38	Slight or moderate blowing snow, generally above eye level
39	Heavy blowing snow, generally above eye level
40 - 49	Fog or ice-fog at the time of observation
40	Fog or ice fog at a distance at the time of observation, but not at the station during the preceding hour, the fog or ice fog extending to a level above that of the observer
41	Fog or ice fog in patches
42	Fog or ice fog, sky visible, has become thinner during the preceding hour
43	Fog or ice fog, sky invisible, has become thinner during the preceding hour
44	Fog of ice fog, sky visible, no appreciable change during the preceding hour
45	Fog or ice fog, sky invisible, no appreciable change during the preceding hour
46	Fog or ice fog, sky visible, has begun or has become thicker during the preceding hour
47	Fog or ice fog, sky invisible, has begun or has become thicker during the preceding hour
48	Fog, depositing rime, sky visible
49	Fog, depositing rime, sky invisible
50 - 59	Drizzle at the station at the time of observation
50	Slight intermittent drizzle (not freezing) at the time of observation
51	Slight continuous drizzle (not freezing) at the time of observation
52	Moderate intermittent drizzle (not freezing) at the time of observation
53	Moderate continuous drizzle (not freezing) at the time of observation
54	Heavy intermittent drizzle (not freezing) at the time of observation
55	Heavy continuous drizzle (not freezing) at the time of observation
56	Slight drizzle (freezing) at the time of observation
57	Moderate or heavy drizzle (freezing) at the time of observation
58	Slight drizzle and rain at the time of observation
59	Moderate or heavy drizzle at the time of observation
60 - 69	Rain at the station at the time of observation
60	Slight intermittent rain (not freezing) at the time of observation
61	Slight continuous rain (not freezing) at the time of observation
62	Moderate intermittent rain (not freezing) at the time of observation
63	Moderate continuous rain (not freezing) at the time of observation
64	Heavy intermittent rain (not freezing) at the time of observation
65	Heavy continuous rain (not freezing) at the time of observation
66	Slight rain (freezing)
67	Moderate or heavy rain (freezing)
68	Slight rain or drizzle and snow
69	Moderate or heavy rain or drizzle and snow
70 - 79	Solid precipitation not in showers at the station at the time of observation
70	Slight intermittent fall of snowflakes at the time of observation
71	Slight continuous fall of snowflakes at the time of observation
72	Moderate intermittent fall of snowflakes at the time of observation
73	Moderate continuous fall of snowflakes at the time of observation
74	Heavy intermittent fall of snowflakes at the time of observation
75	Heavy continuous fall of snowflakes at the time of observation
76	Diamond dust (with or without fog)
77	Snow grains (with or without fog)
78	Isolated star-like snow crystals (with or without fog)
79	Ice pellets
80 - 99	Showery precipitation, or precipitation with current or recent thunderstorm at the station at the time of observation
80	Slight rain shower(s)
81	Moderate or heavy rain shower(s)
82	Violent rain shower(s)
83	Slight shower(s) of rain and snow mixed
84	Moderate or heavy shower(s) of rain and snow mixed
85	Slight snow shower(s)
86	Moderate or heavy snow shower(s)
87	Slight shower(s) of snow pellets or small hail, with or without rain or rain and snow mixed
88	Moderate or heavy shower(s) of snow pellets or small hail, with or without rain or rain and snow mixed
89	Slight shower(s) of hail with or without rain or rain and snow mixed, not associated with thunder
90	Moderate or heavy shower(s) of hail with or without rain or rain and snow mixed, not associated with thunder
91	Slight rain at the time of observation, thunderstorm during the preceding hour but not at the time of observation
92	Moderate or heavy rain at the time of observation, thunderstorm during the preceding hour but not at the time of observation
93	Slight snow, or rain and snow mixed or hail at the time of observation, thunderstorm during the preceding hour but not at the time of observation
94	Moderate or heavy snow, or rain and snow mixed or hail at the time of observation, thunderstorm during the preceding hour but not at the time of observation
95	Slight or moderate thunderstorm without hail, but with rain and/or snow at the time of observation
96	Slight or moderate thunderstorm with hail at the time of observation
97	Heavy thunderstorm without hail, but with rain and/or snow at the time of observation
98	Thunderstorm combined with duststorm or sandstorm at the time of observation
99	Heavy thunderstorm with hail at the time of observation

Top of page

Wind Speed

Symbolic Letter(s) ff - wind speed in the units specified by i_W.

Our wind speed is recorded in km/h but is converted to knots for the synop report. Wind speed is normally reported as a 10 minute average ending at the time of the observation.

On a station weather plot wind speed is represented by a combination of barbs and solid pennants affixed to the end of the wind direction indicator. The full barb represents 10 knots, the half barb represents 5 knots and the pennant represents 50 knots. The barbs and pennants point in the direction of lower pressure, i.e. towards the right of the wind direction indicator in the Southern Hemisphere, and to the left in the Northern Hemisphere.

Code Figure	Description	Weather Symbol
00	displayed on station weather plot as calm
01 or 02	displayed on station weather plot as 2 knots
03 to 07	displayed on station weather plot as 5 knots
08 to 12	displayed on station weather plot as 10 knots
13 to 17	displayed on station weather plot as 15 knots
18 to 22	displayed on station weather plot as 20 knots
23 to 27	displayed on station weather plot as 25 knots
28 to 32	displayed on station weather plot as 30 knots
33 to 37	displayed on station weather plot as 35 knots
38 to 42	displayed on station weather plot as 40 knots
43 to 47	displayed on station weather plot as 45 knots
48 to 52	displayed on station weather plot as 50 knots
53 to 57	displayed on station weather plot as 55 knots
58 to 62	displayed on station weather plot as 60 knots
63 to 67	displayed on station weather plot as 65 knots
68 to 72	displayed on station weather plot as 70 knots
etc	etc	etc

Top of page

[ back ]