Cuaca Nha Trang (Cam Ranh) di September

This coast runs its wet season opposite to most of Vietnam, and January is the month it is climbing out of one. Regulars describe mostly sunny days with some wind and some rain - hit and miss, in their phrase - and our row backs it at 84.3mm across 11.1 days with 8.6 hours of sun. The catch is the water rather than the sky: the sea stays rough into February with high tides, and it is not particularly warm, which our 24.5C confirms against air of 27.3C that reads as 30C. Several say plainly that this is not the month for water sports here. February onwards is when they send people instead. The record: 22.8C nights, humidity 83 percent, a 10.4 kph wind and AQI 51.

April opens the season regulars recommend - roughly April to September - and they also call it the hottest month of the Nha Trang year, with May to July very hot and humid behind it. Our row's 31.1C over a 25.8C night reads as 37C and 32C at 78 percent humidity with almost no wind at 9.4 kph, which makes this among the most oppressive nights in the collection. The tip worth carrying is about water clarity rather than temperature: the break directly in front of town is short and keeps churning sand, so the water there looks brown, while Long Beach further along has a longer break and runs clear. The sea itself is 28.3C. The record: 57.2mm across 10.1 precipitation days, 11 hours of sun and AQI 53.

March is the month Nha Trang's rain is properly behind it - the wet season here lands late in the year rather than in spring, which catches out visitors applying the rest of Vietnam's calendar - and regulars describe it as the point where the swimming gets good again. Their summary is little rain and not yet too hot, with humidity high and constant; residents expect very little to fall across the whole month. March, April and May are the trio they name, and the absence of tropical storms at this time of year is most of why the sea is calm. The record: 29.7C days that feel like 34C, 24.1C nights, 7 precipitation days carrying 41.7mm, humidity 80 percent, 10.9 hours of sun and a 25.7C sea.

Forum posters commonly describe August as reliably sunny with only a short, cooling afternoon shower some days lasting an hour or two - a reputation that holds up only loosely against the real monthly numbers, which show August sitting well within Nha Trang's wetter stretch (May through November), with rainy days nearly as frequent as the September-October peak rather than a clearly dry summer month. Posters are right that any single day's rain here tends to be brief rather than an all-day event, and that the heat and humidity (commonly described as hot bordering on oppressive) are the more consistent day-to-day reality than the rain itself. Posters generally still rate August as good for beach and swimming, just with a genuinely higher rain-day count than the 'sunny all the time' framing implies.