Number of hours of Reduced Visibility observed at
the Hong Kong Observatory since 1968

(criteria: visibility below 8 kilometres, relative humidity < 95%, 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	176	109	113	20	0	51	58	58	191	169	1225
2011	272	190	207	159	101	26	36	50	66	72	75	145	1399
2012	193	93	54	83	14	22	10	144	35	91	63	85	887
2013	214	95	102	112	54	1	0	38	18	76	53	215	978
2014	148	49	124	111	4	17	19	0	27	63	34	26	622
2015	127	162	121	15	7	0	6	48	37	60	13	71	667
2016	38	78	90	84	35	0	10	25	45	14	51	39	509
2017	107	49	128	55	78	0	31	23	79	0	22	73	645
2018	136	41	84	96	14	11	1	53	10	23	22	27	518
2019	91	96	59

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Annual Total
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
Normal (1981 - 2010)	111.5	78.5	86.8	81.1	40.7	11.6	8.6	35.6	46.0	62.8	46.6	82.5	692.3
Mean (1968 - 2018)	98.1	72.7	85.6	77.4	34.6	9.0	7.5	29.2	33.6	45.3	34.0	64.7	591.8

Absolute Maximum in red colour

Column's Maximum in yellow background colour

Fig 1. Annual total number of hours of Reduced Visibility observed at the Hong Kong Observatory

Fig 2. Monthly mean number of hours of Reduced Visibility observed at the Hong Kong Observatory (1981 - 2010 )

Last revision date: <09 Apr 2019>

Number of hours of Reduced Visibility observed atthe Hong Kong Observatory since 1968

Number of hours of Reduced Visibility observed at
the Hong Kong Observatory since 1968