In short
- Season declared on 5 November 2026 across the North, the Chiang Rai Times reports.
- Chiang Mai and Chiang Rai expect some of Thailand's lowest daily temperatures; mountain parks can drop into single digits.
- The first days bring violent thunderstorms and strong gusts over upper Thailand, the North included.
- No visa, entry or transport rule changes; travel north remains possible.
What to do
- 1Pack a warm layer for highland mornings and nights, even if the days stay comfortable.
- 2Check the forecast and road conditions before driving a mountain pass.
- 3Allow slack in your plans for possible flight delays while the storms pass.
- 4Secure loose outdoor items if you are staying in the north during the first days.
What has been declared?
The department declared the season on 5 November 2026, the Chiang Rai Times reported, describing a rapid switch rather than a gradual one. A high-pressure system building over China pushed south into warm, humid air over the north, producing the thunderstorms and gusts reported over upper Thailand, the North included. For month-by-month timing, see when to go.
Where will it be coldest?
Chiang Mai and Chiang Rai are expected to record some of the lowest daily temperatures in the country, with a sharp drop in the evening and early morning while daytime weather stays comfortable. High-altitude areas and national parks can fall into single digits, and highland hotels were reported to be preparing extra blankets and heating devices. For the 2,565 m summit, see the Doi Inthanon guide.
What should travellers watch?
The opening days are the unsettled ones. Heavy thunderstorms can disrupt regional travel schedules, and travellers heading north were advised to watch for flight delays. Drivers were warned about slippery asphalt and reduced visibility on winding mountain roads, with patrols monitoring steep passes. A warm layer and a flexible plan cover most of it; our packing list is built for that.
Travelling soon? Plan around it
Build a day-by-day Thailand route that keeps flexible days where the weather and transport are uncertain.
Sources
We cross-check each story against official pages and several media, and rewrite it in our own words for travellers.
