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September Weather in Vaini Tonga

Daily high temperatures are around 77°F, rarely falling below 73°F or exceeding 82°F.

Daily low temperatures are around 67°F, rarely falling below 61°F or exceeding 72°F.

For reference, on February 13, the hottest day of the year, temperatures in Vaini typically range from 76°F to 85°F, while on August 22, the coldest day of the year, they range from 66°F to 76°F.

Average High and Low Temperature in September in Vaini

Average High and Low Temperature in September in VainiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303060°F60°F62°F62°F64°F64°F66°F66°F68°F68°F70°F70°F72°F72°F74°F74°F76°F76°F78°F78°F80°F80°F82°F82°F84°F84°FAugOctSep 176°FSep 176°F67°F67°FSep 3078°FSep 3078°F68°F68°FSep 1177°FSep 1177°F67°F67°FSep 2177°FSep 2177°F67°F67°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 Vaini

Average Hourly Temperature in September in VainiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 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 AMAugOctcomfortablewarm
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.

Morcellemont Saint André, Mauritius (7,883 miles away) is the far-away foreign place with temperatures most similar to Vaini (view comparison).

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The month of September in Vaini experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 42% throughout the month.

The clearest day of the month is September 5, with clear, mostly clear, or partly cloudy conditions 60% of the time.

For reference, on February 25, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 71%, while on August 8, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 62%.

Cloud Cover Categories in September in Vaini

Cloud Cover Categories in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOctSep 160%Sep 160%Sep 3056%Sep 3056%Sep 1158%Sep 1158%Sep 2157%Sep 2157%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 Vaini, the chance of a wet day over the course of September is essentially constant, remaining around 22% throughout.

For reference, the year's highest daily chance of a wet day is 42% on April 2, and its lowest chance is 15% on June 29.

Probability of Precipitation in September in Vaini

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 Vaini is essentially constant, remaining about 2.6 inches throughout, and rarely exceeding 5.1 inches or falling below 0.5 inches.

Average Monthly Rainfall in September in Vaini

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 Vaini, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 35 minutes, implying an average daily increase of 1 minute, 11 seconds, and weekly increase of 8 minutes, 20 seconds.

The shortest day of the month is September 1, with 11 hours, 43 minutes of daylight and the longest day is September 30, with 12 hours, 17 minutes of daylight.

Hours of Daylight and Twilight in September in Vaini

Hours of Daylight and Twilight in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrAugOctSep 2312 hr, 8 minSep 2312 hr, 8 mindaydaydaydaynightSep 111 hr, 43 minSep 111 hr, 43 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 latest sunrise of the month in Vaini is 6:49 AM on September 1 and the earliest sunrise is 27 minutes earlier at 6:21 AM on September 30.

The earliest sunset is 6:31 PM on September 1 and the latest sunset is 7 minutes later at 6:39 PM on September 30.

Daylight saving time is not observed in Vaini during 2024.

For reference, on December 21, the longest day of the year, the Sun rises at 5:56 AM and sets 13 hours, 26 minutes later, at 7:22 PM, while on June 20, the shortest day of the year, it rises at 7:17 AM and sets 10 hours, 51 minutes later, at 6:07 PM.

Sunrise & Sunset with Twilight in September in Vaini

Sunrise & Sunset with Twilight in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930302 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMAugOct6:21 AM6:21 AMSep 306:39 PMSep 306:39 PM6:49 AM6:49 AMSep 16:31 PMSep 16:31 PM6:39 AM6:39 AMSep 116:34 PMSep 116:34 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 Vaini

Solar Elevation and Azimuth in September in VainiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 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 AMAugOct
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 Vaini

Moon Rise, Set & Phases in September in VainiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMAugOctAug 512:14 AMAug 512:14 AMAug 207:26 AMAug 207:26 AMSep 32:56 PMSep 32:56 PMSep 183:35 PMSep 183:35 PMOct 37:50 AMOct 37:50 AMOct 1812:27 AMOct 1812:27 AM6:57 AM6:57 AM6:03 PM6:03 PM5:48 PM5:48 PM7:13 AM7:13 AM6:47 AM6:47 AM6:35 PM6:35 PM6:40 PM6:40 PM7:05 AM7:05 AM6:20 AM6:20 AM6:57 PM6:57 PM6:25 PM6:25 PM6:16 AM6:16 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%5:37 AMENE4:52 PMWNW-11:15 AMN247,910 mi
2
1%6:14 AMENE5:45 PMWNW-12:00 PMN249,560 mi
3
0%6:47 AMENE6:35 PMW-12:41 PMN250,868 mi
4
1%7:18 AME7:24 PMW-1:21 PMN251,806 mi
5
3%7:48 AME8:12 PMW-1:59 PMN252,324 mi
6
8%8:18 AME9:01 PMW-2:38 PMN252,355 mi
7
14%8:48 AMESE9:50 PMWSW-3:17 PMN251,823 mi
8
21%9:21 AMESE10:42 PMWSW-3:59 PMN250,657 mi
9
30%9:57 AMESE11:36 PMWSW-4:44 PMS248,807 mi
10
40%10:38 AMESE--5:33 PMS246,265 mi
11
50%-12:32 AMWSW11:24 AMESE6:26 PMS243,079 mi
12
60%-1:30 AMWSW12:17 PMESE7:22 PMS239,376 mi
13
71%-2:28 AMWSW1:16 PMESE8:21 PMS235,369 mi
14
81%-3:23 AMWSW2:20 PMESE9:19 PMS231,351 mi
15
89%-4:15 AMWSW3:25 PMESE10:16 PMN227,675 mi
16
96%-5:02 AMWSW4:31 PMESE11:10 PMN224,699 mi
17
98%-5:45 AMWSW5:36 PME--
18
100%-6:25 AMW6:40 PME12:02 AMN222,741 mi
19
100%-7:05 AMW7:43 PME12:53 AMN222,009 mi
20
97%-7:45 AMW8:48 PMENE1:44 AMN222,573 mi
21
91%-8:27 AMWNW9:53 PMENE2:37 AMN224,343 mi
22
83%-9:12 AMWNW11:00 PMENE3:32 AMN227,094 mi
23
73%-10:02 AMWNW-4:30 AMN230,514 mi
24
62%12:05 AMENE10:57 AMWNW-5:30 AMN234,260 mi
25
50%1:07 AMENE11:54 AMWNW-6:31 AMN238,017 mi
26
40%2:04 AMENE12:54 PMWNW-7:29 AMN241,531 mi
27
30%2:54 AMENE1:52 PMWNW-8:23 AMN244,632 mi
28
21%3:37 AMENE2:48 PMWNW-9:13 AMN247,228 mi
29
13%4:16 AMENE3:41 PMWNW-9:59 AMN249,289 mi
30
7%4:50 AMENE4:32 PMWNW-10:41 AMN250,824 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 Vaini is rapidly increasing during September, rising from 39% to 50% over the course of the month.

For reference, on February 13, the muggiest day of the year, there are muggy conditions 100% of the time, while on August 23, the least muggy day of the year, there are muggy conditions 36% of the time.

Humidity Comfort Levels in September in Vaini

Humidity Comfort Levels in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%AugOctSep 139%Sep 139%Sep 3050%Sep 3050%Sep 1144%Sep 1144%Sep 2149%Sep 2149%oppressiveoppressivemuggymuggyhumidhumidcomfortablecomfortabledrydrymiserablemiserable
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 Vaini is essentially constant during September, remaining within 0.2 miles per hour of 14.3 miles per hour throughout.

For reference, on April 25, the windiest day of the year, the daily average wind speed is 15.4 miles per hour, while on February 17, the calmest day of the year, the daily average wind speed is 13.5 miles per hour.

Average Wind Speed in September in Vaini

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

The hourly average wind direction in Vaini throughout September is predominantly from the east, with a peak proportion of 60% on September 27.

Wind Direction in September in Vaini

Wind Direction in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%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).

Vaini 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 Vaini is essentially constant during September, remaining around 75°F throughout.

Average Water Temperature in September in Vaini

Average Water Temperature in September in VainiSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303072°F72°F73°F73°F74°F74°F75°F75°F76°F76°F77°F77°F78°F78°F79°F79°FAugOctSep 174°FSep 174°FSep 3075°FSep 3075°FSep 1174°FSep 1174°FSep 2175°FSep 2175°F
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 Vaini 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 Vaini

Time Spent in Various Temperature Bands and the Growing Season in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%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 16comfortablewarmcool
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 Vaini are rapidly increasing during September, increasing by 623°F, from 1,287°F to 1,910°F, over the course of the month.

Growing Degree Days in September in Vaini

Growing Degree Days in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930301,200°F1,200°F1,300°F1,300°F1,400°F1,400°F1,500°F1,500°F1,600°F1,600°F1,700°F1,700°F1,800°F1,800°F1,900°F1,900°F2,000°F2,000°FAugOctSep 11,287°FSep 11,287°FSep 301,910°FSep 301,910°FSep 111,498°FSep 111,498°FSep 211,713°FSep 211,713°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 Vaini is gradually increasing during September, rising by 0.9 kWh, from 4.9 kWh to 5.9 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in September in Vaini

Average Daily Incident Shortwave Solar Energy in September in VainiSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWhAugOctSep 14.9 kWhSep 14.9 kWhSep 305.9 kWhSep 305.9 kWhSep 115.2 kWhSep 115.2 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 Vaini are -21.193 deg latitude, -175.177 deg longitude, and 30 ft elevation.

The topography within 2 miles of Vaini contains only modest variations in elevation, with a maximum elevation change of 131 feet and an average elevation above sea level of 47 feet. Within 10 miles also contains only modest variations in elevation (253 feet). Within 50 miles contains only modest variations in elevation (1,030 feet).

The area within 2 miles of Vaini is covered by trees (44%), water (29%), shrubs (14%), and grassland (13%), within 10 miles by water (85%), and within 50 miles by water (99%).

This report illustrates the typical weather in Vaini, 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, Fuaʻamotu International Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of Vaini.

At a distance of 5 kilometers from Vaini, 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 Vaini 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.

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