1. WeatherSpark.com
  2. Vietnam
  3. Ha Nội
  4. Hanoi

September Weather in Hanoi Vietnam

Daily high temperatures decrease by 2°F, from 89°F to 87°F, rarely falling below 81°F or exceeding 94°F.

Daily low temperatures decrease by 3°F, from 78°F to 75°F, rarely falling below 71°F or exceeding 81°F.

For reference, on June 26, the hottest day of the year, temperatures in Hanoi typically range from 80°F to 92°F, while on January 19, the coldest day of the year, they range from 57°F to 67°F.

Average High and Low Temperature in September in Hanoi

Average High and Low Temperature in September in HanoiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303060°F60°F65°F65°F70°F70°F75°F75°F80°F80°F85°F85°F90°F90°F95°F95°F100°F100°F105°F105°FAugOctSep 189°FSep 189°F78°F78°FSep 3087°FSep 3087°F75°F75°FSep 1189°FSep 1189°F77°F77°FSep 2188°FSep 2188°F76°F76°F
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature in September in Hanoi

Average Hourly Temperature in September in HanoiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMAugOctcomfortablewarmhotcomfortable
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Laguna Heights, Texas, United States (8,843 miles away) and St. Petersburg, Florida, United States (9,028 miles) are the far-away foreign places with temperatures most similar to Hanoi (view comparison).

Map
Marker
© OpenStreetMap contributors

Compare Hanoi to another city:

Map

The month of September in Hanoi experiences very rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 82% to 63%.

The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 37% of the time.

For reference, on June 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 93%, while on February 22, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 70%.

Cloud Cover Categories in September in Hanoi

Cloud Cover Categories in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOctSep 118%Sep 118%Sep 3037%Sep 3037%Sep 1124%Sep 1124%Sep 2132%Sep 2132%clearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Hanoi, the chance of a wet day over the course of September is very rapidly decreasing, starting the month at 52% and ending it at 31%.

For reference, the year's highest daily chance of a wet day is 57% on August 24, and its lowest chance is 5% on January 31.

Probability of Precipitation in September in Hanoi

Probability of Precipitation in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%0%5%5%10%10%15%15%20%20%25%25%30%30%35%35%40%40%45%45%50%50%55%55%60%60%AugOctSep 152%Sep 152%Sep 3031%Sep 3031%Sep 1146%Sep 1146%Sep 2139%Sep 2139%rain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during September in Hanoi is very rapidly decreasing, starting the month at 8.3 inches, when it rarely exceeds 13.4 inches or falls below 3.3 inches, and ending the month at 4.7 inches, when it rarely exceeds 8.4 inches or falls below 1.5 inches.

Average Monthly Rainfall in September in Hanoi

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Over the course of September in Hanoi, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 34 minutes, implying an average daily decrease of 1 minute, 11 seconds, and weekly decrease of 8 minutes, 17 seconds.

The shortest day of the month is September 30, with 11 hours, 58 minutes of daylight and the longest day is September 1, with 12 hours, 32 minutes of daylight.

Hours of Daylight and Twilight in September in Hanoi

Hours of Daylight and Twilight in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrAugOctSep 2212 hr, 7 minSep 2212 hr, 7 minnightnightdaydaySep 112 hr, 32 minSep 112 hr, 32 min
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in Hanoi is 5:40 AM on September 1 and the latest sunrise is 7 minutes later at 5:47 AM on September 30.

The latest sunset is 6:12 PM on September 1 and the earliest sunset is 27 minutes earlier at 5:45 PM on September 30.

Daylight saving time is not observed in Hanoi during 2024.

For reference, on June 20, the longest day of the year, the Sun rises at 5:15 AM and sets 13 hours, 25 minutes later, at 6:40 PM, while on December 21, the shortest day of the year, it rises at 6:29 AM and sets 10 hours, 51 minutes later, at 5:20 PM.

Sunrise & Sunset with Twilight in September in Hanoi

Sunrise & Sunset with Twilight in September in HanoiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMAugOct5:40 AM5:40 AMSep 16:12 PMSep 16:12 PM5:47 AM5:47 AMSep 305:45 PMSep 305:45 PM5:42 AM5:42 AMSep 116:03 PMSep 116:03 PMSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of September. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth in September in Hanoi

Solar Elevation and Azimuth in September in HanoiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMAugOct0010102020203030404050505060607080000101020203030304040505060607080
northeastsouthwest
Solar elevation and azimuth over the course of September 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for September 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

Moon Rise, Set & Phases in September in Hanoi

Moon Rise, Set & Phases in September in HanoiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMAugOctAug 46:14 PMAug 46:14 PMAug 201:26 AMAug 201:26 AMSep 38:56 AMSep 38:56 AMSep 189:35 AMSep 189:35 AMOct 31:50 AMOct 31:50 AMOct 176:27 PMOct 176:27 PM5:03 AM5:03 AM6:42 PM6:42 PM6:16 PM6:16 PM5:51 AM5:51 AM5:38 AM5:38 AM6:26 PM6:26 PM5:30 PM5:30 PM5:38 AM5:38 AM5:59 AM5:59 AM5:58 PM5:58 PM5:20 PM5:20 PM6:28 AM6:28 AM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.
Sep 2024IlluminationMoonriseMoonsetMoonriseMeridian PassingDistance
1
4%3:53 AMENE5:20 PMWNW-10:39 AMS248,298 mi
2
1%4:47 AMENE5:54 PMWNW-11:22 AMS249,874 mi
3
0%5:38 AME6:26 PMW-12:03 PMS251,105 mi
4
1%6:27 AME6:56 PMW-12:42 PMS251,957 mi
5
4%7:15 AME7:25 PMW-1:21 PMS252,375 mi
6
9%8:03 AME7:55 PMW-1:59 PMS252,290 mi
7
15%8:52 AMESE8:27 PMWSW-2:39 PMS251,626 mi
8
23%9:43 AMESE9:02 PMWSW-3:22 PMS250,314 mi
9
32%10:36 AMESE9:42 PMWSW-4:08 PMS248,311 mi
10
42%11:31 AMESE10:27 PMWSW-4:59 PMS245,620 mi
11
50%12:29 PMESE11:18 PMWSW-5:53 PMS242,306 mi
12
63%1:27 PMESE--6:51 PMS238,513 mi
13
73%-12:16 AMWSW2:23 PMESE7:51 PMS234,473 mi
14
83%-1:18 AMWSW3:16 PMESE8:50 PMS230,498 mi
15
91%-2:23 AMWSW4:04 PMESE9:47 PMS226,943 mi
16
97%-3:29 AMWSW4:49 PMESE10:41 PMS224,168 mi
17
100%-4:34 AMWSW5:30 PME11:33 PMS222,467 mi
18
100%-5:38 AMW6:10 PME--
19
99%-6:41 AMW6:49 PME12:24 AMS222,024 mi
20
96%-7:45 AMWNW7:31 PMENE1:15 AMS222,868 mi
21
90%-8:51 AMWNW8:15 PMENE2:08 AMS224,878 mi
22
81%-9:57 AMWNW9:04 PMENE3:03 AMN227,805 mi
23
70%-11:02 AMWNW9:57 PMENE4:01 AMN231,324 mi
24
59%-12:06 PMWNW10:54 PMENE5:00 AMN235,095 mi
25
50%-1:04 PMWNW11:53 PMENE6:00 AMN238,815 mi
26
37%-1:56 PMWNW-6:56 AMN242,248 mi
27
28%12:52 AMENE2:41 PMWNW-7:49 AMN245,243 mi
28
19%1:49 AMENE3:21 PMWNW-8:37 AMS247,723 mi
29
12%2:43 AMENE3:56 PMWNW-9:22 AMS249,667 mi
30
6%3:34 AMENE4:28 PMW-10:03 AMS251,091 mi

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.

The chance that a given day will be muggy in Hanoi is decreasing during September, falling from 99% to 92% over the course of the month.

For reference, on August 3, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 21, the least muggy day of the year, there are muggy conditions 15% of the time.

Humidity Comfort Levels in September in Hanoi

Humidity Comfort Levels in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%AugOctSep 199%Sep 199%Sep 3092%Sep 3092%Sep 1198%Sep 1198%Sep 2194%Sep 2194%miserablemiserableoppressiveoppressivemuggymuggyhumidhumiddrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 is gradually increasing during September, increasing from 5.5 miles per hour to 6.2 miles per hour over the course of the month.

For reference, on March 10, the windiest day of the year, the daily average wind speed is 7.9 miles per hour, while on August 18, the calmest day of the year, the daily average wind speed is 5.1 miles per hour.

Average Wind Speed in September in Hanoi

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The wind direction in Hanoi during September is predominantly out of the south from September 1 to September 3, the east from September 3 to September 22, and the north from September 22 to September 30.

Wind Direction in September in Hanoi

Wind Direction in September in HanoiSENSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%20%80%40%60%60%40%80%20%100%0%AugOctsoutheastnorthwest
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

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 surface water temperature in Hanoi is essentially constant during September, remaining within 1°F of 84°F throughout.

Average Water Temperature in September in Hanoi

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

Temperatures in Hanoi are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

Time Spent in Various Temperature Bands and the Growing Season in September in Hanoi

Time Spent in Various Temperature Bands and the Growing Season in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOct100%Sep 16100%Sep 16comfortablewarmhotcool
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in Hanoi are very rapidly increasing during September, increasing by 904°F, from 6,188°F to 7,092°F, over the course of the month.

Growing Degree Days in September in Hanoi

Growing Degree Days in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930306,000°F6,000°F6,200°F6,200°F6,400°F6,400°F6,600°F6,600°F6,800°F6,800°F7,000°F7,000°F7,200°F7,200°FAugOctSep 16,188°FSep 16,188°FSep 307,092°FSep 307,092°FSep 116,505°FSep 116,505°FSep 216,818°FSep 216,818°F
The average growing degree days accumulated over the course of September, with 25th to 75th and 10th to 90th percentile bands.

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 in Hanoi is essentially constant during September, remaining within 0.2 kWh of 5.0 kWh throughout.

The highest average daily incident shortwave solar energy during September is 5.2 kWh on September 28.

Average Daily Incident Shortwave Solar Energy in September in Hanoi

Average Daily Incident Shortwave Solar Energy in September in HanoiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWhAugOctSep 285.2 kWhSep 285.2 kWhSep 14.8 kWhSep 14.8 kWhSep 115.0 kWhSep 115.0 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

For the purposes of this report, the geographical coordinates of Hanoi are 21.024 deg latitude, 105.841 deg longitude, and 33 ft elevation.

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 only modest 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.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports and weather stations are provided by AskGeo.com .

Maps are © OpenStreetMap contributors.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.

Please review our full terms contained on our Terms of Service page.