Average Weather in Hanoi Vietnam
In Hanoi, the temperature typically varies from 57°F to 92°F over the course of the year, and is rarely below 49°F or above 99°F.
The hot season lasts for 4.8 months, from May 5 to September 29, with an average daily high temperature above 87°F. The hottest day of the year is June 27, with an average high of 92°F and low of 80°F.
The cool season lasts for 2.7 months, from December 11 to March 2, with an average daily high temperature below 72°F. The coldest day of the year is January 19, with an average low of 57°F and high of 67°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
The length of the day in Hanoi varies over the course of the year. In 2017, the shortest day is December 21, with 10 hours, 51 minutes of daylight; the longest day is June 21, with 13 hours, 25 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:14 AM on June 6, and the latest sunrise is 1 hour, 22 minutes later at 6:36 AM on January 16. The earliest sunset is at 5:13 PM on November 26, and the latest sunset is 1 hour, 28 minutes later at 6:42 PM on July 4.
Daylight saving time (DST) is not observed in Hanoi during 2017.
Sunrise & Sunset with Twilight
In Hanoi, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.
The clearer part of the year in Hanoi begins around October 3 and lasts for 7.0 months, ending around May 4. On February 22, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 70% of the time, and overcast or mostly cloudy 30% of the time.
The cloudier part of the year begins around May 4 and lasts for 5.0 months, ending around October 3. On June 16, the cloudiest day of the year, the sky is overcast or mostly cloudy 93% of the time, and clear, mostly clear, or partly cloudy 7% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Hanoi varies very significantly throughout the year.
The wetter season lasts 5.0 months, from May 4 to October 5, with a greater than 31% chance of a given day being a wet day. The chance of a wet day peaks at 57% on August 25.
The drier season lasts 7.0 months, from October 5 to May 4. The smallest chance of a wet day is 5% on January 30.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 57% on August 25.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day in the year. Hanoi experiences very significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 11 months, from February 18 to January 19, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around August 15, with an average total accumulation of 8.9 inches.
The rainless period of the year lasts for 4.3 weeks, from January 19 to February 18. The least rain falls around February 4, with and average total accumulation of 0.4 inches.
Average Monthly Rainfall
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
Hanoi experiences very significant seasonal variation in the perceived humidity.
The muggier period of the year lasts for 8.9 months, from February 27 to November 25, during which time the comfort level is muggy, oppressive, or miserable at least 36% of the time. The muggiest day of the year is August 10, with muggy conditions 100% of the time.
The least muggy day of the year is January 21, with muggy conditions 15% of the time.
Humidity Comfort Levels
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in Hanoi experiences mildly seasonal variation over the course of the year.
The windier part of the year lasts for 4.9 months, from January 1 to May 28, with average wind speeds of more than 3.5 miles per hour. The windiest day of the year is March 11, with an average hourly wind speed of 4.3 miles per hour.
The calmer time of year lasts for 7.1 months, from May 28 to January 1. The calmest day of the year is August 19, with an average hourly wind speed of 2.8 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Hanoi varies throughout the year.
The wind is most often from the south for 5.6 months, from March 17 to September 4, with a peak percentage of 65% on July 3. The wind is most often from the east for 2.7 weeks, from September 4 to September 23 and for 3.0 months, from December 18 to March 17, with a peak percentage of 50% on February 9. The wind is most often from the north for 2.8 months, from September 23 to December 18, with a peak percentage of 44% on October 28.
Hanoi is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 4.9 months, from May 23 to October 19, with an average temperature above 82°F. The day of the year with the warmest water is August 17, with an average temperature of 85°F.
The time of year with cooler water lasts for 3.3 months, from December 23 to April 2, with an average temperature below 71°F. The day of the year with the coolest water is February 9, with an average temperature of 68°F.
Average Water Temperature
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.
The brighter period of the year lasts for 1.6 months, from March 24 to May 13, with an average daily incident shortwave energy per square meter above 5.3 kWh. The brightest day of the year is April 24, with an average of 5.6 kWh.
The darker period of the year lasts for 2.2 months, from November 23 to February 1, with an average daily incident shortwave energy per square meter below 4.2 kWh. The darkest day of the year is January 8, with an average of 3.9 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Hanoi are 21.024 deg latitude, 105.841 deg longitude, and 39 ft elevation (map ).
The topography within 2 miles of Hanoi contains only modest variations in elevation, with a maximum elevation change of 108 feet, and an average elevation above sea level of 46 feet. Within 10 miles also contains only modest variations in elevation (217 feet). Within 50 miles contains extreme variations in elevation (5,387 feet).
The area within 2 miles of Hanoi is covered by cropland (43%), artificial surfaces (29%), and water (14%), within 10 miles by cropland (60%) and grassland (12%), and within 50 miles by cropland (49%) and trees (23%).
This report illustrates the typical weather in Hanoi, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There is only a single weather station, Noi Bai International Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of Hanoi.
At a distance of 22 kilometers from Hanoi, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.
The station records are corrected for the elevation difference between the station and Hanoi according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .