The best time to travel in Hong Kong has to be understood afresh on a narrow map. There is no long inland expanse here: the whole territory is made up of Hong Kong Island, Kowloon, the New Territories and more than two hundred outlying islands, with hills and sea pressed right up against the city, so that half an hour from your door you can walk from a high-rise to the shore or a ridge. For this reason the seasons in Hong Kong do not show themselves as a dramatic change of scenery; they hide in the small shifts of how the air feels. The same Victoria Harbour night view, seen in October and in July, offers two completely different levels of comfort. The window worth noting in a year is October, November and December: late autumn into winter, when there are many clear days, low humidity and mild temperatures, the least effortful months of the year to be outdoors.
Start with the temperature line. Hong Kong is hottest in July, with an average high of 31.6℃ and an average low of 26.9℃; it is coldest in January, with an average high of 18.7℃ and an average low of 14.6℃. The gap is not large, yet it divides the four seasons clearly. In winter the average high sits around twenty degrees, so a light jacket is enough; in summer the highs stay firmly in the thirties, humid and clinging. The truly comfortable months are October to December: October has an average high of 28.1℃ and a low of 23.9℃, November drops to 24.5℃ and 20.3℃, and December sits at 20.4℃ and 16.2℃, warm in the sun by day and cool at night, so a single light jacket sees you through the whole trip. This is the direct reason the recommended months are October, November and December.
Now the rainfall line, which decides the success of a trip even more than temperature. Hong Kong receives about 2431.2 millimetres of rain a year, of which May to September alone accounts for 1942.5 millimetres, and the three months from June to August add up to 1330.5 millimetres, pushing more than half of the year's rainfall into midsummer. June brings 491.5 millimetres, the most of any month; August follows with 453.2 millimetres, and July with 385.8 millimetres. By contrast, December has only 28.8 millimetres and January 33.2 millimetres, the two driest months of the year. In other words, summer rain is the kind you have to dodge, while winter mostly brings a dryness you can ignore.
Put temperature and rainfall together and Hong Kong's four seasons take on distinct characters. Spring, from March to May, is a season of transition: March has an average high of 21.9℃ and 75.3 millimetres of rain, April climbs to 25.6℃ and 153.0 millimetres, and May reaches 28.8℃ and 290.6 millimetres. Rainfall climbs the whole way, the air grows damper and damper, and now and then there are days of sea fog and returning damp that flatten distant views. This stretch suits slow wandering through the city, but capturing a grand view comes down to luck.
Summer, from June to August, is the season that needs the most planning. Highs often sit around thirty degrees, the humidity is high and the air feels muggy; more crucial still are the typhoons and rainstorms. If you travel in this stretch, put outdoor plans in the early morning and the evening and leave midday to museums and shopping centres, a method locals use too. The upside is that holidays are concentrated here, the islands and beaches are at their liveliest, and the trails are at their greenest.
Autumn, from September to November, is a process of slow improvement. September still has an average high of 30.5℃ and 321.4 millimetres of rain, with neither the heat nor the rain fully gone; in October the high falls back to 28.1℃ and rainfall drops sharply to 120.3 millimetres; November is 24.5℃ and 39.3 millimetres, when the sky begins to clear and the wind begins to dry. By November you can walk half a day along the waterfront in a light jacket without sweating, making it one of the months of the year with the best value for your time.
Winter, from December to February, is Hong Kong's mildest season. December is 20.4℃ and 16.2℃, January 18.7℃ and 14.6℃, February 19.4℃ and 15.3℃, and it rarely drops below ten degrees. There is little rain in this stretch and the sky is occasionally overcast, but none of it gets in the way of shopping, visiting exhibitions or eating a steaming plate of Cantonese cuisine. The mood is at its fullest around Christmas and New Year, when the lights on both banks of Victoria Harbour brighten the night view, making this the liveliest stretch of the year.
If you want to walk the trails, the best value is to set aside the whole of October to December. The hills of Hong Kong, China sit close to the city, and trails often climb all the way up from an MTR exit, so that within half an hour the noise of the streets is thrown behind you. From March to May the hills turn green, but the damp is heavy and sea fog is frequent, so climbing to a ridge often shows you nothing but a white blur; from June to August the rain is most concentrated, the trails turn muddy and thunderstorms come fast, so long walks are unwise. Once October passes, the wind turns dry and visibility returns, and the ridgelines and the outlines of the coast are all clearly defined — the time of the year when a whole day most belongs to the trails.
The stretch that most needs a margin left in it is the turn between summer and autumn. When wind and rain arrive, ferries are often the first to shut down, and the islands and outlying islands bear the brunt; even when the tropical cyclone warning signal does not reach its highest, the wind on the shore and on the ridges is enough to make you unsteady. So for fishing villages and old temples on the outlying islands, it is best to avoid summer and autumn, or to put them before your return and keep a whole spare day afterwards — once the itinerary has a retreat, a gust of wind cannot throw it into disorder. After October the windy season recedes and the sea turns calm, and only then do the outlying islands and bays truly enter their best stretch for walking.
Handing the hottest midday hours and the heaviest rain to indoor spaces is how locals get through summer. The urban areas of Hong Kong, China are thickly set with declared monuments and museums: in the stretch from Central to Sheung Wan, the Former Central Police Station Compound, Man Mo Temple and the Flagstaff House Museum of Tea Ware are within walking distance of one another; over in the old city of Kowloon, the Lei Cheng Uk Han Tomb and Kowloon Walled City Park also let you dodge the sun. Using them as the backbone of a summer itinerary is like taking out insurance for your trip; in the damp days of March and April, indoors is likewise steadier than outdoors. By October the weather is no longer a variable, and these places become all the better for a slow walk and a slow look.
For those sensitive to light, the first thing to watch is not the clouds but the rule by which visibility rises and falls with the seasons. In November, Hong Kong, China has clear skies and dry wind, and looking down from Victoria Peak you can fit both the blocks of buildings along Victoria Harbour and the ridgelines behind them into a single frame; December is drier still, and thin mist often sits on the water in the early morning, which instead gives your shots depth. From March to May the sea fog flattens distant views, and old shop signs and narrow lanes make better subjects then; in June the rain is sudden and the clouds are low, and the reflections after the rain and the pressed-down clouds are subjects unique to midsummer.
If you want the most direct schedule, it can be split into three tiers. First choice, October to December: mild temperatures and the year's least rainfall, so for a first visit to Hong Kong, China, fitting the Victoria Harbour night view, the outlying islands and the trails into these three months is least likely to go wrong. Second choice, March and April: the climate warms again, only it leans damp and rainy, so make the urban areas, monuments and museums the core and the itinerary still runs smoothly. May to September belongs to the humid and typhoon season, suited to islands, water activities and indoor venues, and one more glance at the weather warnings before you go out is always worthwhile.
Three last honest words. Rain in Hong Kong, China comes fast and short, so rather than staring at the day's forecast, it is better to keep a folding umbrella in your bag at all times. Wind and rain in summer and autumn pull flights and ferries around, so leave a stretch of adjustable space in your itinerary and you will not be led by the weather. In any season the gap between indoor and outdoor temperatures is not small — shopping centres and venues run their air conditioning hard, and a light jacket is often more useful than a heavy one. Choose the right time, and dry sunny days, a mild sea breeze and a stretch of days without rushing will all arrive as promised.