3.6 Meteorological Observation Codes

3.6.1 Cloud Development During Past Hour Codes (00-03)

00: Cloud development not observed or not observable

01: Clouds dissolving or becoming less developed

02: State of sky on the whole unchanged

03: Clouds forming or developing

3.6.2 Fog/Precipitation During Past Hour But Not At Time Of Obs (20-28)

20: Drizzle not freezing or snow grains

21: Rain not freezing or snow grains

22: Snow not freezing or snow grains

23: Rain and snow, or ice pellets

24: Drizzle or rain, freezing

25: Showers of rain

26: Showers or snow or of rain and snow

27: Showers of hail or of hail and rain

28: Fog in the past hour, not at present

3.6.3 Blowing or Drifting Snow (36-39)

36: Drifting snow, below eye level, slight/moderate

37: Drifting snow, below eye level, heavy

38: Blowing snow, above eye level, slight/moderate

39: Blowing snow, above eye level, heavy

3.6.4 Fog/ Mist (41-49)

41: Fog in patches, visibility < 1000m

42: Fog thinning in last hour, sky discernible, visibility < 1000m

43: Fog thinning in last hour, sky not discernible, visibility < 1000m

44: Fog unchanged in last hour, sky discernible, visibility < 1000m

45: Fog unchanged in last hour, sky not discernible, visibility < 1000m

46: Fog beginning/thickening in last hour, sky discernible, visibility < 1000m

47: Fog beginning/thickening in last hour, sky not discernible, visibility < 1000m

48: Fog depositing rime, sky discernible, visibility < 1000m

49: Fog depositing rime, sky not discernible, visibility < 1000m

3.6.5 Precipitation As Drizzle (50-59)

50: Slight drizzle, intermittent

51: Slight drizzle, continuous

52: Moderate drizzle, intermittent

53: Moderate drizzle, continuous

54: Dense drizzle, intermittent

55: Dense drizzle, continuous

56: Freezing drizzle, slight

57: Freezing drizzle, moderate or dense

58: Drizzle and rain, slight

59: Drizzle and rain, moderate or dense

3.6.6 Precipitation As Rain, Not Showers (60-69)

60: Slight rain, intermittent

61: Slight rain, continuous

62: Moderate rain, intermittent

63: Moderate rain, continuous

64: Heavy rain, intermittent

65: Heavy rain, continuous

66: Freezing rain, slight

67: Freezing rain, moderate or heavy

68: Rain or drizzle and snow, slight

69: Rain or drizzle and snow, moderate/heavy

3.6.7 Frozen Precipitation, Not Showers (70-79)

70: Slight fall of snow flakes, intermittent

71: Slight fall of snow flakes, continuous

72: Moderate fall of snow flakes, intermittent

73: Moderate fall of snow flakes, continuous

74: Heavy fall of snow flakes, intermittent

75: Heavy fall of snow flakes, continuous

76: Ice prisms, with/without fog

77: Snow grains, with/without fog

78: Isolated starlike snow crystals

79: Ice pellets

3.6.8 Precipitation As Showers (80-90)

80: Slight rain showers

81: Moderate or heavy rain showers

82: Violent rain showers

83: Slight showers of rain and snow

84: Moderate/heavy showers of rain and snow

85: Slight snow showers

86: Moderate or heavy snow showers

87: Slight showers of soft or small hail

88: Moderate/heavy showers of soft/small hail

89: Slight showers of hail

90: Moderate or heavy showers of hail

3.6.9 Visibility Codes

90: < 50 m

91: 50–200 m

92: 200–500 m

93: 500–1000 m

94: 1–2 km

95: 2–4 km

96: 4–10 km

97: > 10 km

-1: Not available