September weather forecastOkayama, Japan

Weather in September

September marks the descent from peak summer with a mild drop in temperature, reaching 28.4°C (83.1°F). There is a resurgence in rainfall, rising to 134mm (5.28") in preparation for the upcoming autumn season. The dropping temperatures and humidity mark a transition toward more comfortable surroundings. This changing weather adds a new layer of color to the city's landscape as the leaves start to change. The sunsets during this shift of seasons are truly breathtaking, creating a beautiful palette across the sky.

Temperature

As Okayama enters September, the average high-temperature subtly lowers from the a hot 32.7°C (90.9°F) of August to a moderately hot 28.4°C (83.1°F). During September nights, Okayama witnesses a consistent average temperature of 20.7°C (69.3°F).

Heat index

In September, the heat index is estimated at a hot 31°C (87.8°F). Persistently participating in activities during exposure may lead to fatigue and induce heat cramps.
Heat index determinations are made taking into account the shade and light air movements. Exposing to direct sunshine may enhance heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'felt air temperature', measures the perceived warmth when incorporating the humidity present in the air. The influence of weather is personal, with varied individuals experiencing it differently due to differences in body mass, stature, and physical exertion levels. Sunshine, when direct, has the potential to intensify weather effects, leading to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for children. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

In Okayama, the average relative humidity in September is 70%.

Rainfall

In Okayama, during September, the rain falls for 17 days and regularly aggregates up to 134mm (5.28") of precipitation. In Okayama, during the entire year, the rain falls for 189 days and collects up to 1106mm (43.54") of precipitation.

Snowfall

In Okayama, snow does not fall in April through December.

Sea temperature

In Okayama, the average seawater temperature in September is 25.8°C (78.4°F).
Note: Surface water temperatures ranging from 25°C (77°F) to 29°C (84.2°F) are considered superb and highly pleasant for water activities over extended periods.

Daylight

In September, the average length of the day is 12h and 24min.
On the first day of the month, sunrise is at 05:37 and sunset at 18:31. On the last day of September, sunrise is at 05:58 and sunset at 17:50 JST.

Sunshine

The average sunshine in September is 5.2h.

UV index

In Okayama, the average daily maximum UV index in September is 8. A UV Index reading of 8 to 10 represents a very high threat to health from exposure to the Sun's UV radiation for the average person.
Note: A daily high UV index of 8 in September leads to these guidelines:
Take the necessary steps to protect yourself; unprotected skin and eyes are vulnerable to damage. 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. Experience reduced UV exposure by about half when donning a wide-brim hat. Be on guard! The reflective nature of sand and water boosts UV exposure.