Snow seen in Vietnam and winter hats worn in Bangkok.
Okinawa, a Japanese island inside the tropics, has been engulfed by a wave of cold.
The largest island in the Ryukyu chain is used to a steady 19 degrees Celsius on a winter day and 14C by night – cold enough for a jacket. A maximum of 10C and minimum of 6C needs more than a jacket and these were Sunday’s temperatures, in the rain.
Okinawa is not used to snow, but 100 metres up on the hill snow fell and the temperature dropped to -5C. Rare though snow is, it is not unprecedented: occasional plunges of Arctic air produced snow in Okinawa in 1952, 1964 and 1977.
In northern Vietnam, where mountain farmers are used to 11C in the winter, snow now covers the vegetables growing on the terraces. The same wave of cold air that swept through China arrived in Vietnam on Sunday and Sa Pa, in Lao Cai province, felt a sudden drop in temperature.
After a nice warm boost on Thursday, with a high of 21C, Saturday showed only 8C in the rain, and Sunday brought snow. It has been sub-zero since Saturday night, dropping to a low of -4C on Sunday night.
Snow is rare in Okinawa, and not unheard of in the mountains of Lao Cai. It has been recorded in five of the past 30 years.
The cold has reached further west and south, through Laos and Myanmar to the Thai capital, Bangkok. This is peak holiday season for foreign visitors to Thailand as it is not too hot, nor too humid, and is normally sunny.
By day Bangkok usually reaches 32C and by night falls to about 23C. On Sunday, a northerly wind brought a little rain and the temperature topped out at 27C. Sunday night saw a dip to 16C. Monday struggled to reach even 20C, and that was under cloudy skies.
Over the next few days, temperatures over Southeast Asia, southern China and Okinawa will return, slowly, to normal. There is, however, still time for a repeat performance of a cold plunge before spring arrives.