No floods up here: why the coast drowns and the plateau does not
Every autumn the news from Vietnam looks the same: boats along the streets of an old town, water up to the first floor, evacuations. That is the coast — and the nearest piece of it is Nha Trang, four hours down the road. On the plateau, a kilometre and a half above the sea, it does not happen — and not by luck but by the shape of the land. Here are the numbers on what floods here, what does not, and what to fear in the mountains instead of water.
The difference in numbers
| What | Da Lat over 35 years → the coast |
|---|---|
| The heaviest single day | 120 mm → over 1,000 mm |
| The heaviest three days | 193 mm → over 1,500 mm |
| 19–21 November 2025, the peak of the Nha Trang flood | 88 mm in Da Lat → about 100,000 buildings under water in Khanh Hoa |
| Annual rainfall | 2,015 mm → up to 2,800 mm in Hue |
| Houses flooded in one episode | no such episodes → 103,525 |
| Evacuation | never → 62,000 people in a single week |
Why water arrives on the coast and leaves in the mountains
Nha Trang, Hoi An, Hue and Da Nang stand in river mouths on the plain by the sea. A typhoon comes ashore, drops a month of rain on the headwaters in a day, the river cannot carry it to the sea fast enough — and spills over a town that lies below its level. The tide adds to it: the water has nowhere to go and it stays until it falls. Da Lat is built the other way round. It sits on a plateau a kilometre and a half up, behind the coastal ridge. A cyclone breaks against the mountains and reaches here as rain rather than wind. The town itself lies on slopes around a lake, and any water that falls on it runs down into the valleys and streams. There is nowhere for it to gather.
Nha Trang, November 2025: four hours away and a completely different weather
Nha Trang is the sea closest to Da Lat and the most common alternative when people choose where to live in Vietnam. Four hours by mountain road lie between the two towns, less than a hundred kilometres as the crow flies. Yet the difference in risk is as if they were in different countries. In the second half of November 2025 the south of central Vietnam was hit by the worst deluge in fifty years. In Khanh Hoa province, whose main town is Nha Trang, about a hundred thousand buildings went under water, the Cai river rose above its historic maximum, and 22 people died. Across the south and centre of the country that week: 90 dead, more than 52,000 houses flooded, some 62,000 people evacuated. In places more than a metre and a half of rain fell in three days. In Da Lat it rained on the same days. Our archive shows 88 millimetres over 19–21 November, and 144 millimetres over the whole eleven days from 15 to 25 November. That is less than a tenth of what the coast took in three days. Wet, grey, laundry that will not dry — and not one evacuation, not one flooded house. This is not a record or an exception: 88 millimetres in three days is an ordinary November here. The heaviest three days in all 35 years of observation brought 193 millimetres — meaning that even Da Lat's all-time maximum is eight times less than what the coast received over the same span that November.
What actually reaches up here
A cyclone within 500 km brings the town heavy rain in 22% of cases, within 150 km in 42%, and in November within 150 km in 64%. The trouble that rain causes is not water in the house but roads and electricity.
- Landslides on the passes. The Prenn pass and the road to Nha Trang — rocks and soil on the tarmac, traffic stopped or down to one lane. That is the main risk of the season, and it is about the road rather than the town.
- Power goes out for hours, longer up in the hills. The dehumidifier, the router and the kettle stop with it — a power bank is not a luxury in such weeks.
- Canyoning and paragliding get cancelled: the river rises and the slopes run. You get the money back, but the day is gone from the plan.
- Flights from Lien Khuong are delayed more often than cancelled: the runway works, but the aircraft does not arrive from Ho Chi Minh City.
- The waterfalls turn into a muddy torrent. There is nothing to look at on such days, and going down to them is dangerous.
Rainfall for Da Lat comes from our own archive of daily observations since 1991, 12,995 days; the annual norm, the daily record, the three-day record and the November 2025 figures are calculated from it. The probabilities of heavy rain during a cyclone are computed from the IBTrACS v04r01 track database (NOAA), 140 systems within 500 km of the town. The coastal figures for 26–29 October 2025 come from Vietnam's Ministry of Natural Resources and Environment as reported by Al Jazeera: over 1,000 mm in 24 hours, 103,525 houses flooded, more than 150 landslides, 3,238 people evacuated in Hue. The figures for Nha Trang and Khanh Hoa in the second half of November 2025 come from Al Jazeera and VnExpress reports of Vietnamese official data: 22 dead in the province and 90 across the south and centre of the country, about 100,000 buildings under water in Khanh Hoa, over 52,000 houses flooded and some 62,000 people evacuated nationally, more than 1,500 mm of rain in three days in places, and a record high on the Cai river. Hue's annual rainfall is open reference data. Our own observations cover Da Lat only: everything said about the coast comes from sources. Checked on 27 August 2026.
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