Weather

Weather might be one of the most important factors you should take into consideration when planning your outings. Do not underestimate how much it can affect your activities.

A placid stream can become mighty rapids. A scenic easy route can transform into walking, and getting lost, in the clouds or too much time under the sun with buddies getting overheat. Easy-ish rock scrambling become a dangerous super slippery rock trap. I guess you get the point.

A lot of people like to criticise the Hong Kong Observatory. I am definitely not one of them. Forecasting in subtropical regions is not easy. In the monsoon season, late May to October, the variability is higher. Hong Kong is relatively small, but nevertheless there can be significant differences among different areas the very same day. In general, highest peaks attract the most intense precipitations. Tai Mo Shan or Lantau Peak, for example, are magnets for clouds. The year rain graph shows clearly the differences.

So, if that is what you are looking for, you have a lower chances of rain if you avoid certain areas. This day for example did not rain at all in Hong Kong but exactly on us on Tai Mo Shan.

Where the anticyclone and low pressure areas are and wind direction can produce rain just in certain zones too. You can access to more detailed information from the HK Observatory with specific area weather situation & forecasts.

It is completely computer generated, a bit less accurate, but can provide you interesting info. When doing really tricky routes I try to check there the latest info: forecasted rain timing, wind speed, lighting track…

Basic principles with examples. If you are with newbies or weaker hikers avoid any extreme weather conditions. If there are chances of heavy rain avoid streams that are prone to flash flooding (explained in the Streams 101).

I am adding a new tag for OK with rain streams. I have hiked those within the rain, sometimes heavy, and were more challenging but doable. Coasteering routes might be tricky if without possible exits in case of a thunderstorm. So if the weather forecast says there are chances of storms avoid routes like Tung Lung Chau‘s.

If you are planning to hike a low flow stream check precipitation levels previous days. If it has not rain at all you might find it dry-ish (Tung Ma To).

If the weather forecast says that might be hazy or very cloudy, you might want to rethink doing any route that is mainly good for its views. Dog’s Tooth for example. You will not see much and it can get dangerous if you do not know the route well enough and you get into dense fog.

If too hot, you should avoid too exposed routes (Pat Sin Leng). Find shaded routes, ideally with several streams to cool into (paths almost to the top of Tai Mo Shan around Tai Shing).

The higher you go the lower the temperature will be. We do not have really high mountains in Hong Kong, but considering that with each one thousand meters elevation gain temperatures decrease by an average of 6.5 degrees Celsius, you can feel significantly cooler on the top of, let’s say, Tai Mo Shan (957 m) vs the city on the sea level.

Pollution can affect hikers. You can check the Air Quality indexes. With poorer air conditions the same route will feel tougher. It will vary from hiker to hiker. The higher you go the less you will be affected. Pollution tends to stay low and it is common to have this view from Lantau Peak…

What should you do if you suddenly see a thunderstorm approaching (count the seconds between the lighting and thunder, 1km per each 3 seconds interval)? Try to find a shelter is the obvious answer. Ideally a solid building, which in Hong Kong would be finding a nearby village, big washroom or similar.

For example on the Maclehose Trail Sec. 8

The open rain shelter is a worse option than the washroom itself. Even if hit by the lighting the electric and plumbing structure will guide it to the earth in the latter. Cars are perfect shelters too.

If you are not able to get to a building, try to minimize chances of being hit. Move to a lower ground, out of open spaces where you are the highest thing around, far from water bodies, switch off your gadgets and separate from metallic objects (this could be your backpack or poles if old style), they will not attract the lighting, but can worsen the effects if hit by one. If in a group, separate 20m apart, to minimize the chances of more than one hiker being hit by a single lighting. Keep calm, don’t get injured trying to go downhill too fast, nor let any hiker behind. If you feel the lighting is going to hit around (tinkling sensation, vibration of small metallic stuff) crouch and cover your eyes and ears.

More info about lighting safety, how the HKObservatory thunderstorm alert works. More preparations to consider before your adventure.