Average Weather in Okayama Japan
In Okayama, the summers are warm, oppressive, wet, and mostly cloudy and the winters are chilly, windy, and mostly clear. Over the course of the year, the temperature typically varies from 34°F to 88°F and is rarely below 28°F or above 93°F.
The hot season lasts for 2.9 months, from June 23 to September 21, with an average daily high temperature above 80°F. The hottest day of the year is August 5, with an average high of 88°F and low of 76°F.
The cool season lasts for 3.4 months, from December 5 to March 16, with an average daily high temperature below 55°F. The coldest day of the year is January 26, with an average low of 34°F and high of 46°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
In Okayama, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Okayama begins around September 15 and lasts for 6.7 months, ending around April 5. On December 18, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 75% of the time, and overcast or mostly cloudy 25% of the time.
The cloudier part of the year begins around April 5 and lasts for 5.3 months, ending around September 15. On July 2, the cloudiest day of the year, the sky is overcast or mostly cloudy 72% of the time, and clear, mostly clear, or partly cloudy 28% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Okayama varies significantly throughout the year.
The wetter season lasts 3.6 months, from June 8 to September 26, with a greater than 35% chance of a given day being a wet day. The chance of a wet day peaks at 51% on July 2.
The drier season lasts 8.4 months, from September 26 to June 8. The smallest chance of a wet day is 18% on January 23.
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 51% on July 2.
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 of the year. Okayama experiences extreme seasonal variation in monthly rainfall.
Rain falls throughout the year in Okayama. The most rain falls during the 31 days centered around June 29, with an average total accumulation of 7.9 inches.
The least rain falls around January 1, with an average total accumulation of 1.5 inches.
Average Monthly Rainfall
The length of the day in Okayama varies significantly over the course of the year. In 2017, the shortest day is December 22, with 9 hours, 50 minutes of daylight; the longest day is June 21, with 14 hours, 29 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 4:50 AM on June 13, and the latest sunrise is 2 hours, 21 minutes later at 7:11 AM on January 7. The earliest sunset is at 4:53 PM on December 5, and the latest sunset is 2 hours, 28 minutes later at 7:21 PM on June 29.
Daylight saving time (DST) is not observed in Okayama during 2017.
Sunrise & Sunset with Twilight
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.
Okayama experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 3.8 months, from June 7 to September 30, during which time the comfort level is muggy, oppressive, or miserable at least 25% of the time. The muggiest day of the year is August 5, with muggy conditions 98% of the time.
The least muggy day of the year is February 8, when muggy conditions are essentially unheard of.
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 Okayama experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 5.2 months, from November 15 to April 20, with average wind speeds of more than 4.3 miles per hour. The windiest day of the year is January 19, with an average hourly wind speed of 5.4 miles per hour.
The calmer time of year lasts for 6.8 months, from April 20 to November 15. The calmest day of the year is June 15, with an average hourly wind speed of 3.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Okayama varies throughout the year.
The wind is most often from the north for 2.2 months, from February 11 to April 18 and for 2.6 months, from August 29 to November 18, with a peak percentage of 48% on October 7. The wind is most often from the west for 1.7 weeks, from April 18 to April 30; for 1.7 weeks, from July 4 to July 16; and for 2.8 months, from November 18 to February 11, with a peak percentage of 36% on July 11. The wind is most often from the south for 2.2 months, from April 30 to July 4 and for 1.4 months, from July 16 to August 29, with a peak percentage of 35% on July 23.
Okayama 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 significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 2.7 months, from July 14 to October 4, with an average temperature above 76°F. The day of the year with the warmest water is August 22, with an average temperature of 81°F.
The time of year with cooler water lasts for 4.6 months, from December 17 to May 6, with an average temperature below 62°F. The day of the year with the coolest water is February 24, with an average temperature of 57°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 significant seasonal variation over the course of the year.
The brighter period of the year lasts for 4.6 months, from April 12 to August 30, with an average daily incident shortwave energy per square meter above 5.4 kWh. The brightest day of the year is May 23, with an average of 6.1 kWh.
The darker period of the year lasts for 3.0 months, from November 11 to February 10, with an average daily incident shortwave energy per square meter below 3.2 kWh. The darkest day of the year is December 26, with an average of 2.5 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Okayama are 34.650 deg latitude, 133.933 deg longitude, and 13 ft elevation.
The topography within 2 miles of Okayama contains significant variations in elevation, with a maximum elevation change of 531 feet and an average elevation above sea level of 44 feet. Within 10 miles contains significant variations in elevation (1,693 feet). Within 50 miles contains very significant variations in elevation (5,430 feet).
The area within 2 miles of Okayama is covered by grassland (35%), artificial surfaces (27%), trees (16%), and cropland (12%), within 10 miles by cropland (45%) and trees (35%), and within 50 miles by trees (51%) and water (35%).
This report illustrates the typical weather in Okayama, 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 Okayama.
For each station, the records are corrected for the elevation difference between that station and Okayama 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 Okayama is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Okayama and a given station.
The stations contributing to this reconstruction are: Tokushima Airport (50%, 85 kilometers, southeast); Miho–Yonago Airport (32%, 113 kilometers, northwest); and Marine Corps Air Station Iwakuni (18%, 166 kilometers, west).
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.