Short answer
Expect fog, drizzle and cool air. Visit for atmosphere and Tet festivities, and keep plans flexible because boat views can disappear completely.
01Weather
Temperatures sit around 15–19 °C with high humidity. The famous Gulf of Tonkin drizzle, mưa phùn, is light but persistent, and sea fog can reduce visibility to a few hundred metres. Occasional bright days do happen, usually after a cold front passes.
02Tet and crowds
In years when the Lunar New Year falls in February, the island goes quiet over the holiday itself as families gather at home, then fills up with Vietnamese visitors in the days that follow. Transport and rooms are busier and pricier during that week. Outside Tet, February is very quiet.
03On the water
Boats run, but fog can cancel or shorten trips for safety. Choose a flexible operator and avoid paying in advance for a multi-day cruise if you can. Swimming is not recommended with the sea around 19 °C.
?Questions people ask
Is Cat Ba foggy in February?
Often. February and March are the foggiest months, with low cloud and drizzle that can last for several days.
Do boats run during Tet?
Most do, though some small operators take a break. Book through your hotel to be sure.