vietnam weather: the north

The North

The dry season
The dry season, from October to May, is divided into three periods. From October to November, it is comfortable and dry. From December to February, it is considerably cooler, and can sometimes be bitingly cold with persistent light drizzle, locally known as ‘mua bui’ – ‘rain dust’. Skies are grey in late January and early February, but warm bright spells do occur. The average temperature is about 20°C but can fall to 6°C or 7°C at night. From March to May, it is much warmer and drier, and can sometimes be quite hot.

The wet season
The rainy season is from June to September - the wettest months are July and August. In the past, violent tropical storms were a regular occurrence – indeed, some tourist guide books still warn against them. In reality, there has been a marked climate change in recent years – the last serious storm occurred in 1999. Spectacular thunderstorms are common, but are not much of a problem if you avoid the deluge that comes with them.

Hanoi's weather	Jan	Feb	Mar	Apr	May	June	July	Aug	Sept	Oct	Nov	Dec
Mean high temperature (˚C)	20	20	23	27	32	33	32	32	31	29	26	22
Mean high temperature (˚F)	69	69	74	81	89	91	90	90	88	84	78	72
Mean low temperature (˚C)	14	14	17	21	24	26	26	26	24	22	18	15
Mean low temperature (˚F)	57	58	63	69	75	78	78	78	76	71	65	59
Rainfall in inches	0.7	1.0	1.8	3.3	7.6	9.4	11.6	12.2	10.1	5.0	1.8	0.8
Average percentage humidity	73	76	80	79	73	75	76	79	76	72	71	71

Different weather in the northwest
In the northwest mountainous area, January and February are the coldest months. There are significant amounts of fog at that time, and even an occasional flurry of snow. Sapa is one of the few places in Viet Nam where hotels have fireplaces!

From March to early May, and from September to December, the weather is excellent but from June to August heavy rain makes climbing Mt. Fansipan and other peaks hazardous. Trekking is possible, but heavy rain and thick mud makes it very strenuous and uncomfortable.
Unfortunately, weather records for the Sa Pa and Lau Chai are unavailable

The small town of Muong Bu, near Son La, is about half-way between Hanoi and Dien Bien Phu in an area where the mountains are lower. It’s about 115km to the south of Sa Pa as the crow flies but at a similar elevation. The weather patterns are similar.

Weather statistics are not available for Ha Long Bay. However, the weather in the bay area is much like that of Hanoi, about the same temperatures but slightly less rain. The only significance is light onshore breeze that makes the peak summer temperatures and humidity more bearable.

Extreme weather
The north is subject to the occasional typhoon, but at this distance from the Equator, they have weakened and seldom cause serious damage. Of more concern are localised phenomena that can cause loss of life. For example, although the weather may be warm and sunny in the northern mountains, earlier heavy rain higher in the mountains can cause sudden flash flooding of the streams and rivers in the valleys.

To guard against such accidents, we always work with the best local operators and guides, as they have detailed knowledge of the area, and particularly of the weather patterns. A skilled local guide is able to anticipate such dangers and either use a contingency plan, or if necessary, abort the activity if there is any possibility of danger.

The same principle applies in Ha Long. Although Ha Long Bay is sheltered by its many islands, sometimes an abrupt localised squall can overturn even boats. We use only large licensed boats with full safety certificates and equipment including ship-to-shore communication, crewed by people who know the bay inside out and never take risks.