Frost has happened at the highest point in Thailand- Doi Inthanon Mountain just north of Chiang Mai.
The cold weather has lead to 35 provinces being declared cold weather disaster zones. For a farang, the weather in a place like Chiang Mai would still be warm- the temperature range for this week is 16 C to 31 C (60 F = 16 C). But, Thailand- and Thai people- is not equipped to handle the cool temperature.
And, this shows how the body adapts to the climate. The Thai people can handle the extreme heat, humidity and sun, but not the cooler temperature.
Evolution in action?