Ha Long's weather is mild and pleasant during the winter months, with temperatures ranging from 8-24°C in January. As spring approaches, temperatures rise gradually, reaching averages of 21-30°C by April and May. Summer brings sweltering heat, with June to August experiencing highs of up to 39°C, but the temperature cools down slightly in September. Autumn is mild once more, with November's average temperature returning to around 22°C. Winters are cooler, with December's averages dipping back down to around 19°C.