 |

Number of hours of Reduced Visibility observed at the Hong Kong Observatory since 1968
(criteria: visibility below 8 kilometres when there is no fog, mist, or precipitation)
| Year |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual Total |
| 1968 | 15 | 9 | 61 | 53 | 2 | 0 | 0 | 3 | 4 | 0 | 0 | 11 | 158 |
| 1969 | 46 | 48 | 101 | 109 | 7 | 9 | 0 | 3 | 2 | 0 | 0 | 5 | 330 |
| 1970 | 37 | 54 | 69 | 81 | 37 | 5 | 0 | 18 | 0 | 0 | 1 | 14 | 316 |
| 1971 | 15 | 21 | 61 | 65 | 3 | 0 | 0 | 6 | 6 | 0 | 1 | 6 | 184 |
| 1972 | 59 | 55 | 33 | 32 | 29 | 2 | 0 | 1 | 0 | 4 | 0 | 10 | 225 |
| 1973 | 19 | 38 | 65 | 62 | 2 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 188 |
| 1974 | 12 | 70 | 25 | 30 | 2 | 0 | 0 | 1 | 3 | 0 | 1 | 5 | 149 |
| 1975 | 7 | 42 | 60 | 35 | 2 | 1 | 0 | 1 | 2 | 3 | 0 | 4 | 157 |
| 1976 | 6 | 45 | 28 | 51 | 46 | 0 | 0 | 0 | 0 | 0 | 0 | 17 | 193 |
| 1977 | 44 | 48 | 98 | 12 | 11 | 1 | 1 | 0 | 0 | 0 | 0 | 13 | 228 |
| 1978 | 33 | 59 | 87 | 79 | 17 | 6 | 1 | 0 | 0 | 0 | 0 | 10 | 292 |
| 1979 | 72 | 48 | 58 | 108 | 43 | 3 | 1 | 5 | 0 | 5 | 0 | 45 | 388 |
| 1980 | 58 | 62 | 108 | 83 | 36 | 3 | 7 | 2 | 2 | 15 | 1 | 1 | 378 |
| 1981 | 27 | 68 | 103 | 38 | 5 | 0 | 1 | 6 | 3 | 1 | 30 | 17 | 299 |
| 1982 | 42 | 78 | 109 | 46 | 27 | 17 | 3 | 2 | 3 | 24 | 0 | 1 | 352 |
| 1983 | 24 | 28 | 27 | 95 | 19 | 3 | 0 | 17 | 7 | 1 | 0 | 48 | 269 |
| 1984 | 61 | 35 | 58 | 71 | 52 | 4 | 0 | 8 | 3 | 2 | 0 | 13 | 307 |
| 1985 | 69 | 66 | 66 | 68 | 7 | 18 | 0 | 7 | 2 | 10 | 0 | 15 | 328 |
| 1986 | 44 | 23 | 43 | 42 | 27 | 3 | 1 | 55 | 3 | 0 | 1 | 38 | 280 |
| 1987 | 33 | 50 | 46 | 31 | 12 | 3 | 0 | 0 | 0 | 4 | 3 | 45 | 227 |
| 1988 | 59 | 30 | 55 | 45 | 26 | 0 | 0 | 0 | 8 | 20 | 24 | 28 | 295 |
| 1989 | 60 | 53 | 26 | 56 | 10 | 25 | 0 | 36 | 2 | 52 | 6 | 85 | 411 |
| 1990 | 34 | 48 | 55 | 28 | 12 | 14 | 0 | 16 | 8 | 0 | 9 | 50 | 274 |
| 1991 | 48 | 73 | 77 | 64 | 31 | 2 | 5 | 89 | 20 | 0 | 19 | 67 | 495 |
| 1992 | 59 | 41 | 71 | 54 | 48 | 3 | 0 | 8 | 32 | 11 | 21 | 115 | 463 |
| 1993 | 27 | 134 | 62 | 57 | 48 | 5 | 5 | 35 | 79 | 2 | 10 | 34 | 498 |
| 1994 | 192 | 65 | 79 | 48 | 5 | 0 | 7 | 51 | 30 | 0 | 6 | 20 | 503 |
| 1995 | 78 | 32 | 49 | 91 | 31 | 8 | 10 | 22 | 8 | 5 | 38 | 87 | 459 |
| 1996 | 112 | 36 | 49 | 48 | 30 | 0 | 29 | 11 | 28 | 85 | 39 | 114 | 581 |
| 1997 | 145 | 51 | 125 | 124 | 54 | 29 | 18 | 84 | 44 | 115 | 53 | 132 | 974 |
| 1998 | 110 | 32 | 103 | 45 | 9 | 16 | 0 | 5 | 121 | 9 | 82 | 87 | 619 |
| 1999 | 158 | 86 | 81 | 36 | 47 | 27 | 2 | 55 | 44 | 69 | 105 | 40 | 750 |
| 2000 | 144 | 96 | 129 | 59 | 38 | 0 | 14 | 5 | 8 | 18 | 23 | 89 | 623 |
| 2001 | 110 | 79 | 81 | 88 | 75 | 13 | 8 | 31 | 104 | 79 | 41 | 18 | 727 |
| 2002 | 128 | 102 | 80 | 41 | 46 | 10 | 34 | 63 | 102 | 61 | 43 | 118 | 828 |
| 2003 | 228 | 136 | 156 | 97 | 94 | 26 | 0 | 7 | 21 | 114 | 109 | 129 | 1117 |
| 2004 | 218 | 168 | 98 | 180 | 77 | 61 | 27 | 129 | 138 | 223 | 102 | 149 | 1570 |
| 2005 | 350 | 94 | 108 | 237 | 26 | 14 | 23 | 68 | 163 | 160 | 172 | 87 | 1502 |
| 2006 | 230 | 173 | 138 | 132 | 30 | 1 | 31 | 62 | 41 | 250 | 90 | 79 | 1257 |
| 2007 | 148 | 90 | 68 | 115 | 130 | 16 | 1 | 62 | 152 | 173 | 38 | 305 | 1298 |
| 2008 | 107 | 168 | 173 | 123 | 54 | 2 | 31 | 1 | 127 | 154 | 58 | 102 | 1100 |
| 2009 | 110 | 130 | 112 | 165 | 39 | 9 | 9 | 82 | 20 | 184 | 84 | 195 | 1139 |
| 2010 | 191 | 89 | | | | | | | | | | | |
Normal (1971 - 2000) |
61.7 | 53.8 | 67.9 | 56.8 | 24.3 | 6.5 | 3.5 | 17.6 | 15.6 | 15.2 | 15.7 | 41.2 | 379.6 |
Mean (1968 - 2009) | 85.2 | 68.2 | 78.1 | 74.4 | 32.0 | 8.6 | 6.4 | 25.2 | 31.9 | 44.1 | 28.8 | 58.3 | 541.2 |
Mean (1968 - 2010) | 87.7 | 68.7 | | | | | | | | | | | |
| Year |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual Total |
|
Absolute Maximum in red colour
|
|
Column's Maximum in yellow background colour
|
|