The best time to visit Vietnam

What a year in Vietnam looks like

Vietnam is longer than most maps make it feel. The north has a genuinely cold winter and thick hill fog; the centre's wet season arrives later and brings storms late in the year; the south has only a dry season and a wet one and stays hot throughout. A single trip from Hanoi down to Ho Chi Minh City therefore usually means accepting that one region will not be at its best.

The year, in windows

• October to December (north): Hanoi and the northern highlands are at their driest and coolest, with clear skies and easy overland travel. The terraces have been harvested and visibility in the mountains is good. Late December turns cold with fog settling in the high valleys.
• February to May (centre): Da Nang and Hoi An are at their best: sunny, a calm sea, and not yet as hot as full summer. It is the window where a beach day and a walk round the old town fit into the same day.
• December to April (south): The dry season in Ho Chi Minh City and the Mekong Delta: little rain and easy travel on the water. Temperatures stay high throughout but nothing interrupts the schedule. March and April are the hottest of these months.
• September to November (centre): The stretch to watch. The centre gets heavy rain and can take storms in these months, which affects domestic flights and the coastal road. If your route passes Da Nang or Hue then, build in a spare day.

The weeks to aim for

March and April give the best overall result if you are covering the whole country in one trip: the north has warmed up, the centre is at its best and the south is still dry — traded against higher heat in the south than at other times.

The weeks to avoid

Tet, the lunar new year, when many businesses close for days and the country travels home at once; domestic trains and flights sell out well ahead. Unless the festival is why you came, avoid that week.

What the season does to a data plan

Cities and main corridors have good coverage all year; the northern mountains and small southern islands are where it thins. Storm season in the centre brings local power cuts, which affect hotel Wi-Fi more than the mobile network.