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Average Weather in September in Okinawa Japan

In Okinawa, the month of September is characterized by gradually falling daily high temperatures, with daily highs decreasing by 3°F, from 88°F to 85°F over the course of the month, and rarely exceeding 91°F or dropping below 81°F.

Daily low temperatures decrease by 4°F, from 79°F to 75°F, rarely falling below 70°F or exceeding 82°F.

For reference, on July 19, the hottest day of the year, temperatures in Okinawa typically range from 80°F to 89°F, while on January 26, the coldest day of the year, they range from 57°F to 66°F.

Average High and Low Temperature in September

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

Average Hourly Temperature in September in Okinawa1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM4 AM8 AM12 PM4 PM8 PM12 AMAugOctcomfortablehotwarm
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.


The month of September in Okinawa experiences very rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 62% to 45%.

The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 55% of the time.

For reference, on June 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 81%, while on December 17, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 69%.

Cloud Cover Categories in September

Cloud Cover Categories in September in Okinawa181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOctSep 138%Sep 138%Sep 3055%Sep 3055%Sep 1142%Sep 1142%Sep 2148%Sep 2148%clearovercastmostly clearpartly cloudymostly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.


A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Okinawa, the chance of a wet day over the course of September is essentially constant, remaining around 37% throughout.

For reference, the year's highest daily chance of a wet day is 57% on June 4, and its lowest chance is 22% on December 19.

Probability of Precipitation in September

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).


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 Okinawa is decreasing, starting the month at 5.9 inches, when it rarely exceeds 11.6 inches or falls below 1.5 inches, and ending the month at 5.3 inches, when it rarely exceeds 10.4 inches or falls below 1.2 inches.

Average Monthly Rainfall in September

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 liquid-equivalent snowfall.


Over the course of September in Okinawa, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 44 minutes, implying an average daily decrease of 1 minute, 32 seconds, and weekly decrease of 10 minutes, 41 seconds.

The shortest day of the month is September 30, with 11 hours, 56 minutes of daylight and the longest day is September 1, with 12 hours, 40 minutes of daylight.

Hours of Daylight and Twilight in September

Hours of Daylight and Twilight in September in Okinawa181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrAugOctSep 2312 hr, 8 minSep 2312 hr, 8 minnightnightdaydaySep 112 hr, 40 minSep 112 hr, 40 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 Okinawa is 6:08 AM on September 1 and the latest sunrise is 12 minutes later at 6:20 AM on September 30.

The latest sunset is 6:48 PM on September 1 and the earliest sunset is 32 minutes earlier at 6:16 PM on September 30.

Daylight saving time is not observed in Okinawa during 2017.

For reference, on June 21, the longest day of the year, the Sun rises at 5:36 AM and sets 13 hours, 48 minutes later, at 7:24 PM, while on December 21, the shortest day of the year, it rises at 7:12 AM and sets 10 hours, 29 minutes later, at 5:41 PM.

Sunrise & Sunset with Twilight in September

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.


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 Okinawa is rapidly decreasing during September, falling from 99% to 87% over the course of the month.

For reference, on July 8, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 13, the least muggy day of the year, there are muggy conditions 3% of the time.

Humidity Comfort Levels in September

Humidity Comfort Levels in September in Okinawa181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%10%20%30%40%50%60%70%80%90%100%AugOctSep 199%Sep 199%Sep 3087%Sep 3087%Sep 1197%Sep 1197%Sep 2193%Sep 2193%oppressiveoppressivehumidhumiddrydrymuggymuggymiserablemiserablecomfortablecomfortable
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.


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 Okinawa is gradually increasing during September, increasing from 7.0 miles per hour to 8.0 miles per hour over the course of the month.

For reference, on December 2, the windiest day of the year, the daily average wind speed is 9.0 miles per hour, while on May 22, the calmest day of the year, the daily average wind speed is 6.6 miles per hour.

Average Wind Speed in September

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 Okinawa throughout September is predominantly from the east, with a peak proportion of 45% on September 27.

Wind Direction in September

Wind Direction in September in OkinawaEN181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOcteastnorthsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Okinawa 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 Okinawa is gradually decreasing during September, falling by 2°F, from 84°F to 82°F, over the course of the month.

Average Water Temperature in September

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

Solar Energy

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 Okinawa is essentially constant during September, remaining within 0.2 kWh of 5.2 kWh throughout.

Average Daily Incident Shortwave Solar Energy in September

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 Okinawa are 26.336 deg latitude, 127.801 deg longitude, and 167 ft elevation.

The topography within 2 miles of Okinawa contains only modest variations in elevation, with a maximum elevation change of 400 feet and an average elevation above sea level of 233 feet. Within 10 miles contains only modest variations in elevation (715 feet). Within 50 miles contains significant variations in elevation (1,650 feet).

The area within 2 miles of Okinawa is covered by cropland (71%) and trees (14%), within 10 miles by water (75%) and cropland (13%), and within 50 miles by water (96%).

Data Sources

This report illustrates the typical weather in Okinawa year round, 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 are 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Okinawa.

For each station, the records are corrected for the elevation difference between that station and Okinawa according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Okinawa is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Okinawa and a given station.

The stations contributing to this reconstruction are: Kadena Air Base (80%, 3.8 kilometers, northwest); Marine Corps Air Station Futenma (20%, 9 kilometers, southwest); and Okinoerabu Airport (0.3%, 151 kilometers, northeast).

Other Data

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 .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.