Climate - Hanoi (Vietnam)

In Hanoi, the capital of Vietnam, there is a subtropical climate, with very mild winters and hot, humid and rainy summers. The sun shines quite rarely. The rainiest period is from June to September, due to the monsoon of Southeast Asia.
The city is located in northern Vietnam, at 21 degrees north latitude, at the beginning of the Red River Delta and about 90 km (55 mi) from the coast of the Gulf of Tonkin.
The winter, from December to February, is mild, however, the sky is often cloudy, especially in January and February, and drizzle can occur. Furthermore, in this season the pollution is often high.
Winter averages are a little higher than in the far north of Vietnam, however, sometimes there can be very cool periods here as well, with lows around 7/8 °C (45/46 °F) and highs around 15 °C (59 °F). More rarely, it can even get cold for a few days, and highs can drop to around 10 °C (50 °F). In January 2016, there was a day with a minimum of 5 °C (41 °F) and a maximum of 8 °C (46.5 °F). In the mountain massif of Ba Vì, which is located about 40 km (25 mi) west of the city and measures 1,296 meters (4,252 feet) in height, it even snowed on that occasion.
In April and May, before the monsoon, it can get very hot, but also from June to September, in the pauses between a period of bad weather and the next. At the beginning of June 2017, the temperature reached 41 °C (106 °F).
The summer, from May to September, is hot and muggy, with frequent and sometimes heavy rains.
Here are the average temperatures.

On average, about 1,600 mm (63 in) of rain fall per year, of which more than 150 mm (6 in) per month fall in May and October, and more than 250 mm (10 in) from June to September. Although precipitation in winter is weak, as mentioned, especially from January onwards, there are frequent drizzles.
Here is the average precipitation.

Hanoi is a dull city, in fact, the sun is rarely seen from January to April, but even in summer, it does not shine very often because of the summer monsoon. There are about 1,585 hours of sunshine per year. Here are the sunshine hours per day.

On the coast near Hanoi (see Haiphong), the sea is a bit cool from January to March, while it is very warm in the summer months. Anyway, in winter, cool and cloudy weather conditions which prevail in this season are usually not inviting for swimming.

The city can be hit by typhoons, the tropical cyclones of Southeast Asia, even though it is not on the coast, which is the area most at risk. Typically, typhoons pass in this area from late May to early November, with a maximum from July to October.

Best Time

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In Hanoi, there is no time of year when the temperatures are mild, the sun shines and there is little rain. However, you can choose spring and autumn, and in particular, from mid-March to mid-April and from the end of October to the end of November.
In winter, December is a little sunnier and less cool than January and February.

Hanoi - Weather by month

Based on the period 1991-2020

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In January, the coldest month of the year, the weather in Hanoi is usually very mild. The average temperature is of 17.1 °C (63 °F), with a minimum of 14.1 °C (57.4 °F) and a maximum of 20.1 °C (68.2 °F).
On the coldest nights of the month, the temperature usually drops to around 8.5 °C (47.5 °F).
On the warmest days of the month, the temperature usually reaches around 27.5 °C (81.5 °F).
Precipitation amounts to 20 mm (0.8 in), distributed over 10 days.
The day lasts on average 11 hours and 0 minutes.
There are on average 2.5 hours of sunshine per day. So, the sun shines 22% of the time.
The average humidity is 78%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In February, the weather in Hanoi is usually warm. The average temperature is of 18.6 °C (66 °F), with a minimum of 15.8 °C (60.4 °F) and a maximum of 21.5 °C (70.7 °F).
On the coldest nights of the month, the temperature usually drops to around 10.5 °C (51 °F).
On the warmest days of the month, the temperature usually reaches around 28.5 °C (83.5 °F).
Precipitation amounts to 20 mm (0.8 in), distributed over 12 days.
The day lasts on average 11 hours and 30 minutes.
There are on average 1.5 hours of sunshine per day. So, the sun shines 15% of the time.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).

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In March, the weather in Hanoi is usually warm. The average temperature is of 21 °C (70 °F), with a minimum of 18.3 °C (64.9 °F) and a maximum of 23.7 °C (74.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 12.5 °C (54.5 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 30.5 °C (87 °F).
Precipitation amounts to 35 mm (1.4 in), distributed over 16 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 1.5 hours of sunshine per day. So, the sun shines 13% of the time.
The average humidity is 85%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In April, the weather in Hanoi is usually warm to hot and muggy. The average temperature is of 24.9 °C (77 °F), with a minimum of 21.7 °C (71.1 °F) and a maximum of 28 °C (82.5 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 16.5 °C (62 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 34 °C (93.5 °F).
Precipitation amounts to 105 mm (4.1 in), distributed over 14 days.
The day lasts on average 12 hours and 35 minutes.
There are on average 3 hours of sunshine per day. So, the sun shines 24% of the time.
The average humidity is 84%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).

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In May, the weather in Hanoi is usually very hot and muggy. The average temperature is of 28.2 °C (83 °F), with a minimum of 24.4 °C (75.9 °F) and a maximum of 32 °C (89.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 20.5 °C (69 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 37.5 °C (99 °F).
Precipitation amounts to 165 mm (6.5 in), distributed over 14 days.
The day lasts on average 13 hours and 5 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 45% of the time.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 11 kph (7 mph).

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In June, the hottest month of the year, the weather in Hanoi is usually very hot and muggy. The average temperature is of 30.0 °C (86 °F), with a minimum of 26.1 °C (78.9 °F) and a maximum of 34 °C (93.2 °F).
On the coldest nights, the temperature usually drops to around 23 °C (73.5 °F).
On the warmest days, the temperature usually reaches around 38 °C (100.5 °F).
Precipitation amounts to 265 mm (10.4 in), distributed over 15 days.
The day lasts on average 13 hours and 25 minutes. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 5.5 hours of sunshine per day. So, the sun shines 43% of the time.
The average humidity is 79%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In July, the weather in Hanoi is usually very hot and muggy. The average temperature is of 29.9 °C (86 °F), with a minimum of 26.2 °C (79.1 °F) and a maximum of 33.6 °C (92.5 °F).
On the coldest nights of the month, the temperature usually drops to around 23.5 °C (74 °F).
On the warmest days of the month, the temperature usually reaches around 37.5 °C (100 °F).
Precipitation amounts to 255 mm (10 in), distributed over 16 days.
The day lasts on average 13 hours and 20 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 10 kph (6 mph).

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In August, the weather in Hanoi is usually very hot and muggy. The average temperature is of 29.3 °C (85 °F), with a minimum of 25.8 °C (78.4 °F) and a maximum of 32.9 °C (91.2 °F).
On the coldest nights of the month, the temperature usually drops to around 23 °C (73.5 °F).
On the warmest days of the month, the temperature usually reaches around 36.5 °C (98 °F).
Precipitation amounts to 275 mm (10.8 in), distributed over 17 days.
The day lasts on average 12 hours and 50 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 44% of the time.
The average humidity is 84%. Hence, the air is normally humid.
The average wind speed is 9 kph (5 mph).

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In September, the weather in Hanoi is usually very hot and muggy. The average temperature is of 28.4 °C (83 °F), with a minimum of 24.8 °C (76.6 °F) and a maximum of 32 °C (89.6 °F).
On the coldest nights, the temperature usually drops to around 22 °C (71.5 °F).
On the warmest days, the temperature usually reaches around 35.5 °C (95.5 °F).
Precipitation amounts to 245 mm (9.6 in), distributed over 14 days.
The day lasts on average 12 hours and 10 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 48% of the time.
The average humidity is 81%. Hence, the air is normally humid.
The average wind speed is 8 kph (5 mph).

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In October, the weather in Hanoi is usually warm to hot and muggy. The average temperature is of 26.0 °C (79 °F), with a minimum of 22.2 °C (72 °F) and a maximum of 29.8 °C (85.6 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 17.5 °C (63.5 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 33.5 °C (92.5 °F).
Precipitation amounts to 155 mm (6.1 in), distributed over 11 days.
The day lasts on average 11 hours and 35 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 8 kph (5 mph).

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In November, the weather in Hanoi is usually warm to hot and muggy. The average temperature is of 22.6 °C (73 °F), with a minimum of 18.8 °C (65.8 °F) and a maximum of 26.4 °C (79.5 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 14 °C (57 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 31.5 °C (88.5 °F).
Precipitation amounts to 60 mm (2.4 in), distributed over 8 days.
The day lasts on average 11 hours and 5 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 41% of the time.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 9 kph (5 mph).

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In December, the weather in Hanoi is usually warm. The average temperature is of 18.6 °C (65 °F), with a minimum of 15 °C (58.9 °F) and a maximum of 22.2 °C (71.9 °F).
On the coldest nights of the month, the temperature usually drops to around 9.5 °C (49 °F).
On the warmest days of the month, the temperature usually reaches around 28.5 °C (83 °F).
Precipitation amounts to 20 mm (0.8 in), distributed over 5 days.
The day lasts on average 10 hours and 55 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 4 hours of sunshine per day. So, the sun shines 37% of the time.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is 9 kph (6 mph).