September weather forecast
Yonaguni, Japan

September, the first month of the autumn in Yonaguni, is also a moderately hot month, with an average temperature varying between 29.8°C (85.6°F) and 25.1°C (77.2°F).

Temperature

As September takes hold, the average high-temperature is a moderately hot 29.8°C (85.6°F), nearly mirroring that of the previous month. September registers an average low temperature of 25.1°C (77.2°F) in Yonaguni, subtly lower than the daytime maximum.

Heat index

During September, the heat index is evaluated at a sweltering 37°C (98.6°F). Use additional protective measures, heat cramps and heat exhaustion are possible outcomes. Continuous activity might lead to heatstroke.
Observations indicate that the heat index values are for shady locations with light wind. Facing direct sunlight may hike up the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', melds the effects of warmth and moisture to generate a feeling of heat. Factors such as metabolic variations, being pregnant, and physical activity can impact an individual's weather perception. Consider the fact that direct sun exposure can influence how hot one feels, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital for children. Youngsters typically face more danger than adults since they sweat less. Their larger skin surface compared to their small bodies and heightened heat production from their activities augment their vulnerability.
The primary way humans combat excessive warmth is by perspiring, letting sweat evaporate and cool the body. When the air holds a significant amount of moisture, the efficiency of the evaporation process is decreased, preventing the body from cooling down efficiently, leading to the sensation of overheating. As the body gains more heat than it can dissipate, there's a risk of increasing temperatures and resultant overheating.

Humidity

The average relative humidity in September in Yonaguni is 79%.

Rainfall

The month with the most rainfall is September, when 293mm (11.54") of precipitation is typically aggregated.

Sea temperature

In September, the average sea temperature in Yonaguni is 28.5°C (83.3°F).
Note: Temperatures between 25°C (77°F) and 29°C (84.2°F) in water are ideal for swimming, diving, and other activities, providing enjoyment and comfort for extended durations.

Daylight

The average length of the day in September is 12h and 18min.
On the first day of September in Yonaguni, Japan, sunrise is at 06:29 and sunset at 19:06. On the last day of the month, sunrise is at 06:39 and sunset at 18:36 JST.

Sunshine

In Yonaguni, the average sunshine in September is 6.1h.