Do you need to know, when is the best time to go to Hong Kong? Then you should take a look here, what weather you can expect there during the year.
The climate of Hong Kong is subtropical. Monsoon influences the weather. The weather here is usually cool and humid in winter, but hot and rainy from spring through summer. You can expect some rains during summer, typhoons occur sometimes as well. You can expect warm and sunny weather in fall.
When speaking about the usual weather in this state, the information is relevant for example for these popular places: Cheung Chau, Peng Chau.
Let's look now what weather you can expect in the area around the capital and in many other cities. The warmest month here is August, the average maximum temperature is 31.7 ℃ (89.06 ℉). The average minimum temperature in this month is 26.8 ℃ (80.24 ℉). The coldest month here is January, the average maximum temperature is 19.1 ℃ (66.38 ℉). The average minimum temperature in this month is 14.9 ℃ (58.82 ℉). The most rainy month here is June, the average number of rainy days is 18.7. The least rainy month here is December, the average number of rainy days is 4.5. 
When travelling to some places in Hong Kong, always consider the altitude of the the place as well. The highest point here is Tai Mo Shan (958 m) and the lowest point is South China Sea (0 m). So there are not big differences in altitudes in this country. But the altitude affects the weather even so. Keep in mind, that the temperature usually decreases by 1.2 - 1.9 ℃ (2.2 - 3.5 ℉) per 200 m (656 ft), depending on the other conditions. (And we should add, that in the very special condition named thermal inversion even the temperature may be higher in higher altitudes.)
Typical (usual) weather in Hong Kong in January is this: The average highest temperature in Hong Kong in January is 19.1 ℃ (66.38 ℉). The average lowest temperature is 14.9 ℃ (58.82 ℉). At the beginning of January you can expect higher temperatures, the average highest temperature is around 19.6 ℃ (67.28 ℉). At the end of January you can expect lower temperatures, the average highest temperature is around 19.1 ℃ (66.38 ℉). The average number of rainy days in January is 5.5. The average rainfall is 25.2 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 10:47 (hours and minutes), in the middle of the month 10:54 and at the end of the month 11:07.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in February is this: The average highest temperature in Hong Kong in February is 19.1 ℃ (66.38 ℉). The average lowest temperature is 15.3 ℃ (59.54 ℉). At the beginning of February you can expect lower temperatures, the average highest temperature is around 19.1 ℃ (66.38 ℉). At the end of February you can expect higher temperatures, the average highest temperature is around 20.2 ℃ (68.36 ℉). The average number of rainy days in February is 9. The average rainfall is 54.4 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:07 (hours and minutes), in the middle of the month 11:24 and at the end of the month 11:42.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in March is this: The average highest temperature in Hong Kong in March is 21.3 ℃ (70.34 ℉). The average lowest temperature is 17.4 ℃ (63.32 ℉). At the beginning of March you can expect lower temperatures, the average highest temperature is around 20.2 ℃ (68.36 ℉). At the end of March you can expect higher temperatures, the average highest temperature is around 23 ℃ (73.4 ℉). The average number of rainy days in March is 10.6. The average rainfall is 82.3 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:42 (hours and minutes), in the middle of the month 12:01 and at the end of the month 12:21.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.
Typical (usual) weather in Hong Kong in April is this: The average highest temperature in Hong Kong in April is 24.7 ℃ (76.46 ℉). The average lowest temperature is 20.6 ℃ (69.08 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 23 ℃ (73.4 ℉). At the end of April you can expect higher temperatures, the average highest temperature is around 26.35 ℃ (79.43 ℉). The average number of rainy days in April is 12.1. The average rainfall is 172.9 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:21 (hours and minutes), in the middle of the month 12:39 and at the end of the month 12:57.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in May is this: The average highest temperature in Hong Kong in May is 28 ℃ (82.4 ℉). The average lowest temperature is 23.8 ℃ (74.84 ℉). At the beginning of May you can expect lower temperatures, the average highest temperature is around 26.35 ℃ (79.43 ℉). At the end of May you can expect higher temperatures, the average highest temperature is around 28.95 ℃ (84.11 ℉). The average number of rainy days in May is 14.6. The average rainfall is 310.5 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:57 (hours and minutes), in the middle of the month 13:12 and at the end of the month 13:23.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.
Typical (usual) weather in Hong Kong in June is this: The average highest temperature in Hong Kong in June is 29.9 ℃ (85.82 ℉). The average lowest temperature is 26.5 ℃ (79.7 ℉). At the beginning of June you can expect lower temperatures, the average highest temperature is around 28.95 ℃ (84.11 ℉). At the end of June you can expect higher temperatures, the average highest temperature is around 30.75 ℃ (87.35 ℉). The average number of rainy days in June is 18.7. The average rainfall is 452 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 13:23 (hours and minutes), in the middle of the month 13:29 and at the end of the month 13:29.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in July is this: The average highest temperature in Hong Kong in July is 31.6 ℃ (88.88 ℉). The average lowest temperature is 27.1 ℃ (80.78 ℉). At the beginning of July you can expect lower temperatures, the average highest temperature is around 30.75 ℃ (87.35 ℉). At the end of July you can expect higher temperatures, the average highest temperature is around 31.65 ℃ (88.97 ℉). The average number of rainy days in July is 17.8. The average rainfall is 367.7 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 13:29 (hours and minutes), in the middle of the month 13:22 and at the end of the month 13:11.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in August is this: The average highest temperature in Hong Kong in August is 31.7 ℃ (89.06 ℉). The average lowest temperature is 26.8 ℃ (80.24 ℉). At the beginning of August you can expect lower temperatures, the average highest temperature is around 31.65 ℃ (88.97 ℉). At the end of August you can expect lower temperatures, the average highest temperature is around 30.85 ℃ (87.53 ℉). The average number of rainy days in August is 16.6. The average rainfall is 436.1 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 13:11 (hours and minutes), in the middle of the month 12:56 and at the end of the month 12:39.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in September is this: The average highest temperature in Hong Kong in September is 30 ℃ (86 ℉). The average lowest temperature is 26.1 ℃ (78.98 ℉). At the beginning of September you can expect higher temperatures, the average highest temperature is around 30.85 ℃ (87.53 ℉). At the end of September you can expect lower temperatures, the average highest temperature is around 29.3 ℃ (84.74 ℉). The average number of rainy days in September is 14.8. The average rainfall is 332.7 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:39 (hours and minutes), in the middle of the month 12:20 and at the end of the month 12:01.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in October is this: The average highest temperature in Hong Kong in October is 28.6 ℃ (83.48 ℉). The average lowest temperature is 24.1 ℃ (75.38 ℉). At the beginning of October you can expect higher temperatures, the average highest temperature is around 29.3 ℃ (84.74 ℉). At the end of October you can expect lower temperatures, the average highest temperature is around 26.7 ℃ (80.06 ℉). The average number of rainy days in October is 7.4. The average rainfall is 102.5 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:01 (hours and minutes), in the middle of the month 11:42 and at the end of the month 11:24.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in November is this: The average highest temperature in Hong Kong in November is 24.8 ℃ (76.64 ℉). The average lowest temperature is 19.8 ℃ (67.64 ℉). At the beginning of November you can expect higher temperatures, the average highest temperature is around 26.7 ℃ (80.06 ℉). At the end of November you can expect lower temperatures, the average highest temperature is around 22.45 ℃ (72.41 ℉). The average number of rainy days in November is 5.6. The average rainfall is 37.5 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:24 (hours and minutes), in the middle of the month 11:08 and at the end of the month 10:55.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.Typical (usual) weather in Hong Kong in December is this: The average highest temperature in Hong Kong in December is 20.1 ℃ (68.18 ℉). The average lowest temperature is 16.5 ℃ (61.7 ℉). At the beginning of December you can expect higher temperatures, the average highest temperature is around 22.45 ℃ (72.41 ℉). At the end of December you can expect lower temperatures, the average highest temperature is around 19.6 ℃ (67.28 ℉). The average number of rainy days in December is 4.5. The average rainfall is 26.4 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 10:55 (hours and minutes), in the middle of the month 10:47 and at the end of the month 10:46.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes.