High-Altitude Travel Weather and Altitude Sickness: Tibet, Western Sichuan and the Yunnan–Guizhou Plateau

Lhasa, Xining, Daocheng, Shangri-La and Lijiang are the destinations whose city pages on this site most often carry the notes “day–night swing above 12°C” and “UV very high”. Plateau weather follows rules quite unlike the lowlands: a single day can run from blazing sun to hail and back to sunshine, a city can see 22°C at noon and 3°C at night, and forecasts miss by more. Yet the thing that matters more than the weather is altitude sickness, because it decides whether you can enjoy any of it. This article brings together the character of plateau weather, seasonal advice, and how preventing altitude sickness and preparing for the weather turn out to be the same task. The medical content is general knowledge and does not replace a doctor’s advice.

1. Five features of plateau weather

First, large day–night swings. Above 3,000 metres the air is thin and dry: direct sun heats the ground fast by day, radiation cools it fast at night, and swings of 15–20°C are normal — a Lhasa summer day of 25°C followed by an 8°C night is routine. Second, extremely strong UV. Each 1,000 metres of altitude adds roughly 10–12% to UV intensity, and with clear air plus reflection off snow and water, Lhasa’s summer UV index regularly exceeds 11, the “extreme” band. Third, fast changes. Afternoon convection is vigorous, and in summer the plateau often produces a short shower, a thunderstorm or even hail around two or three o’clock, clearing within the hour. Fourth, wind. March to May is the windy season, with force 6–8 winds common in Qinghai and northern Tibet that drive the feels-like temperature far below the reading. Fifth, dryness. Outside the summer rains, relative humidity sits at 20–40%, and cracked lips, nosebleeds and flaking skin are common complaints.

2. Choosing a season

May to June is the first good window: the rains have not arrived, days run 15–22°C, the sky is transparent and rhododendrons and alpine flowers bloom; the drawbacks are cold mornings and evenings and snow still lying on some high passes. July to August is high season and rainy season together — the most comfortable days at 20–25°C and the greenest grassland, but showers almost every afternoon; rising humidity actually eases altitude symptoms slightly, while crowds, prices and the risk of landslides on mountain roads after rain all climb. September to mid-October is the second window and, for many, the best: the rains end, visibility is the year’s finest, autumn colour peaks, days sit at 12–20°C and mornings already touch freezing, so a down jacket is required. November to April is the off season, with mild days of 5–12°C and much sunshine but nights below −10°C, less oxygen than in summer, and some sites and roads closed; it suits experienced travellers only. The Yunnan–Guizhou plateau is lower (1,800–2,400 m): Kunming, Dali and Lijiang work year-round, and the only rule is to avoid the June-to-September rains.

3. What altitude sickness is, and how weather feeds into it

Altitude sickness is the cluster of symptoms the body produces before it has adapted to low oxygen: headache, nausea, fatigue, poor sleep and loss of appetite, usually appearing 6–24 hours after arriving above 2,500 metres and easing within two or three days for most people. Its severe forms — high-altitude pulmonary and cerebral oedema — show as persistent cough, breathlessness and confusion and demand immediate descent and medical care. Weather feeds in through several routes. Cold raises the body’s oxygen demand and can trigger or worsen symptoms, one reason winter trips to Tibet are riskier. Colds and stomach upsets brought on by big day–night swings aggravate altitude sickness sharply. Dryness leads to dehydration, itself a major trigger. Strong wind and falling pressure ahead of storms make many people feel worse. On the plateau, protecting yourself from the weather and from altitude sickness are one and the same.

4. Nine measures that prevent altitude sickness

One: ascend in stages — a night or two in a 2,000–3,000 m city such as Xining or Nyingchi, or the train, beats flying straight into Lhasa. Two: for the first two days no showers, no running, no alcohol, no early starts; plan half as much as usual. Three: drink two to three litres of water a day, because dehydration on a dry plateau is silent. Four: warmth before looks — carry a down jacket and hat and put them on before sunset, not after you feel cold. Five: eat light and carbohydrate-rich, never to fullness. Six: keep the bedroom ventilated rather than hot and stuffy. Seven: if you have a history of altitude sickness or want preventive medication, consult a doctor beforehand; acetazolamide, the usual drug, is prescription-only and has contraindications. Eight: treat a headache with ibuprofen or paracetamol as directed and do not force yourself to sleep through it; if symptoms have not eased by the third day or are worsening, descending to lower altitude is the only reliable remedy. Nine: do not go higher in the first three days — arriving in Lhasa and heading straight to Namtso at 4,700 m is the classic mistake.

5. A concrete clothing and protection list

Dress the upper body in three layers: a wicking base, a fleece or light down mid-layer, a wind- and waterproof shell; strip to one by day and add back before sunset. For the legs, quick-dry trousers plus fleece trousers cover May to October; winter needs insulated trousers. Choose a brimmed hat for sun and warmth together, and sunglasses marked UV400 without fail — half a day unprotected by snow or a lake can cause snow blindness. Use SPF 50+ sunscreen reapplied every two hours and a lip balm with sun protection. Shoes must grip and shed water; plateau scree and post-rain mud are slippery. In the day bag: an insulated bottle, lip balm, sunscreen, a light down jacket, a rain jacket (umbrellas are useless in the wind), your usual medicines and a pulse oximeter. Oximeters are cheap, and a saturation below 80% with symptoms is a clear signal to descend.

6. Reading forecasts on the plateau

Forecasts for plateau cities miss by more than in the lowlands because model grids cannot resolve complex terrain; our article on seven-day forecast reliability explains why. Three practical rules: pack for the forecast low minus 3°C; in summer, treat any “shower” or “thunderstorm” symbol as rain between two and five in the afternoon and put outdoor activity in the morning; and when the forecast wind exceeds 8 m/s, keep away from passes and lakeshores that day. The UV index on our city pages is estimated from latitude and conditions and runs low for the plateau, so prepare for “extreme” regardless. The cold-risk index sits at “high” or above on the plateau almost permanently — a true reflection of the swing and the dryness, not a false alarm.

7. Altitude and climate at a glance for the main destinations

Lhasa, 3,650 m, mean annual temperature 8°C: June to September days of 20–25°C; winter days of 8–12°C but nights of −10°C; UV extreme all year. Xining, 2,260 m, the ideal acclimatisation stop before Tibet, 22–28°C in summer and one of China’s coolest provincial capitals. Daocheng–Yading, 3,700–4,700 m, autumn colour peaking in early October — also the busiest time for altitude sickness, because visitors come straight up from Chengdu at 500 m. Shangri-La, 3,300 m, rhododendrons in May–June and colour in September–October, wet in summer. Lijiang, 2,400 m, rarely causes altitude sickness; winter days of 15°C and nights of 0°C make it the country’s textbook day–night swing. Kunming, 1,900 m, the mildest climate of all, with the single caveat that UV is already strong from March to May. Qinghai Lake, 3,200 m, rapeseed in bloom in July and August, windy, and in need of a thick jacket even in summer.