September weather forecast
Naha, Japan

September in Naha, brings about a subtle shift in weather conditions, signaling the end of summer. Gradual decline in temperatures becomes evident, indicating the approach of autumn. However, precipitation peaks this month with rainfall of 261mm (10.28"), making September the month with the highest rainfall. The gradually decreasing daylight hours induce an atmospheric change, dressing the cityscape in spectacular twilight hues. Even with decreasing temperatures, sea temperatures remain at comfortable levels, enriching the experience for water sport enthusiasts and beach lovers.

Temperature

Naha registers an average high-temperature of a still tropical 30.4°C (86.7°F) at the commencement of September, closely related to the preceding month. Naha encounters an average temperature dip to a warm 25.5°C (77.9°F) throughout September, subtly lower than its daytime maximum.

Heat index

September's heat index is estimated at a very hot 38°C (100.4°F). Incorporate special precautions, risk of heat exhaustion and heat cramps is substantial. Sustained activity could cause heatstroke.
Note that heat index values are valued for light wind and location in the shade. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is a value derived by merging air temperature with the humidity to convey how the climate feels. Factors such as metabolic variations, being pregnant, and physical activity can impact an individual's weather perception. Taking into account that direct sunlight can boost the heat effect, the heat index may rise by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are of high significance for children. Children often miss understanding the importance of rest and rehydration. Thirst usually appears late during dehydration - therefore, maintaining hydration, particularly during long physical activities, is essential.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. Excessive relative humidity disturbs the body's typical cooling process by reducing evaporation, leading to a decrease in body cooling rate and an increase in the sensation of warmth. When body temperature rises due to an imbalance in heat gain, there's a potential for dehydration and overheating.

Humidity

The average relative humidity in September is 76%.

Rainfall

The month with the most rainfall is September, when the rain falls for 12.5 days and typically aggregates up to 261mm (10.28") of precipitation.

Sea temperature

In Naha, in September, the average water temperature is 28.3°C (82.9°F).
Note: Swimming, diving, and other water activities in temperatures ranging from 25°C (77°F) to 29°C (84.2°F) are highly enjoyable and provide prolonged comfort without unease.

Daylight

In Naha, the average length of the day in September is 12h and 19min.
On the first day of September in Naha, Japan, sunrise is at 06:09 and sunset at 18:49. On the last day of the month, sunrise is at 06:21 and sunset at 18:17 JST.

Sunshine

In September, the average sunshine in Naha is 6.3h.

UV index

In September, the average daily maximum UV index is 10. A UV Index of 8 to 10 symbolizes a very high health risk from exposure to the Sun's UV rays for average individuals.
Note: In September, the maximum UV index of 10 suggests this advice:
Be sure to take precautions. Without protection, skin might suffer damage quickly. Remember that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. Make an effort to avoid direct sun exposure during these hours. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. After a swim or an outdoor workout, generously apply and reapply a broad-spectrum SPF 30+ sunscreen. Caution! The Sun's UV intensity grows with reflections off sand and water.