September weather forecast
Hiroshima, Japan

September brings a pleasant change to Hiroshima's weather with temperatures beginning to tone down from the summer highs. While the rainfall shows an uptick from August, it does not match the intense monsoon-like conditions of June or July. A decrease in humidity levels introduces a more comfortable environment compared to the sultry summertime. The daylight hours start reducing slowly as the year heads towards the end. The UV index also draws back indicating lesser intensity of sun rays compared to previous months.

Temperature

September implies a soft temperature shift, with average high-temperatures reducing from August's tropical 32.5°C (90.5°F) to a moderately hot 29°C (84.2°F). Nighttime temperature experiences an average drop to a pleasant 20.8°C (69.4°F) in September.

Heat index

For most parts of September, the heat index is appraised at a hot 33°C (91.4°F). Incorporate additional preventive steps, heat exhaustion and heat cramps are possible. Long-lasting activity may cause heatstroke.
Metrics for the heat index primarily focus on shaded spots and light wind conditions. Exposure to direct sunlight may make the heat index values climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'apparent temperature', is an aggregate value of air's warmth and moisture to show the human-felt temperature. One's weather perception can be influenced by a range of factors including metabolic differences, being pregnant, and their level of physical activity. Keep in mind that direct sunshine exposure can amplify the weather's effects, possibly increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are largely significant for babies and toddlers. Young ones often ignore the need to take a break and drink fluids. Thirst is a late-stage symptom of dehydration - hence, maintaining hydration, particularly during extended physical activities, is crucial.

Humidity

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

Rainfall

In Hiroshima, during September, the rain falls for 16 days and regularly aggregates up to 170mm (6.69") of precipitation. Throughout the year, there are 190 rainfall days, and 1538mm (60.55") of precipitation is accumulated.

Snowfall

In Hiroshima, snow does not fall in April through November.

Sea temperature

In Hiroshima, in September, the average water temperature is 25.5°C (77.9°F).
Note: Between the temperatures of 25°C (77°F) and 29°C (84.2°F), water is considered very warm, providing pleasure in water activities without discomfort over lengthy periods.

Daylight

In September, the average length of the day in Hiroshima is 12h and 24min.
On the first day of the month, sunrise is at 05:43 and sunset at 18:36. On the last day of September, sunrise is at 06:04 and sunset at 17:56 JST.

Sunshine

In September, the average sunshine is 5.5h.

UV index

The average daily maximum UV index in September in Hiroshima is 8. A UV Index estimate of 8 to 10 represents a very high threat to health from exposure to the Sun's UV rays for average individuals.
Note: In September, the maximum UV index of 8 translates into these guidelines:
Swift harm can befall unprotected skin and eyes. Prioritize safety. Limit your direct sun exposure, especially between 10 a.m. and 4 p.m., when UV radiation is strongest. Shade structures might not provide complete sun protection. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Heads up! The reflection of sand and water notably intensifies UV rays from the Sun.