September weather forecast
Osaka, Japan

In September, a gradual cooling trend sets in from the height of Osaka's summer heat. While the temperature slowly decreases, rainfall exhibits an opposite pattern, resulting in heavier showers compared to the previous month. Longer daytime hours, found during the peak summer months, start to recede, yet still allowing ample outdoor activities. The slight cooling combined with persistent rain paints September as a transitioning season in Osaka. This month is synonymous with fading summer warmth and coming autumn rainfall.

Temperature

September heralds a minor drop in average high-temperature, sliding from August's hot 33.4°C (92.1°F) to a warm 29.3°C (84.7°F). September brings an average low-temperature of 21.7°C (71.1°F) to Osaka.

Heat index

September's average heat index is appraised at a hot 33°C (91.4°F). Greater safety measures are needed, risk of heat exhaustion and heat cramps is high. Continuous activity might trigger heatstroke.
When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. The heat index could see an increase by 15 Fahrenheit (8 Celsius) degrees under direct sunshine.
Note: The heat index, also known as 'real feel' or 'felt air temperature', is a numerical representation of warmth when taking temperature and moisture levels into account. One's perception of temperature can vary depending on physical activity and individual heat sensitivity, influenced by factors like wind, attire, and metabolic variations. One must note that being under the direct sun can escalate the heat's effects, with the heat index possibly rising by 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely vital to babies and toddlers. Youths are typically more endangered than adults since they usually sweat less. Their larger skin surface concerning their smaller bodies and higher heat production due to activity further adds to their vulnerability.

Humidity

In Osaka, the average relative humidity in September is 67%.

Rainfall

In September, in Osaka, the rain falls for 9.4 days. Throughout September, 161mm (6.34") of precipitation is accumulated. Throughout the year, there are 98.1 rainfall days, and 1279mm (50.35") of precipitation is accumulated.

Snowfall

In Osaka, snow does not fall in March through December.

Sea temperature

In September, the average sea temperature in Osaka is 26.3°C (79.3°F).
Note: In water temperatures ranging between 25°C (77°F) and 29°C (84.2°F), activities such as swimming and diving become highly pleasurable for long durations.

Daylight

In September, the average length of the day is 12h and 24min.
On the first day of the month, sunrise is at 05:31 and sunset at 18:24. On the last day of September, sunrise is at 05:51 and sunset at 17:43 JST.

Sunshine

In September, the average sunshine in Osaka is 5.2h.

UV index

In Osaka, the average daily maximum UV index in September is 8. A UV Index reading of 8 to 10 represents a very high health hazard from exposure to the Sun's UV rays for the average person.
Note: The maximum UV index of 8 during September translates into these guidelines:
Take important precautions because unprotected skin can burn and be harmed swiftly. The time between 10 a.m. and 4 p.m. is when UV radiation is at its peak. Limit exposure to direct sunlight during these hours. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck. Heed this! UV intensity is much stronger when reflected off sand and water.