Weather in Iwakuni

Get the latest weather information for Iwakuni. Here you will find up-to-date forecasts, current data, and useful charts to help you plan your day.

The climate in Iwakuni, located in Japan, can be described as temperate with four distinct seasons. The city experiences significant temperature fluctuations throughout the year, which is typical for this climatic zone. Visitors should expect varied weather conditions depending on the timing of their trip.

Winters in Iwakuni (December–February) are cool, with average temperatures around 5-6°C and relatively low rainfall. Spring (March–May) brings gradual warming and some increase in rain. Summer (June–August) in Iwakuni is warm and noticeably more humid, with average temperatures reaching 27°C in August. This period, especially July, is characterised by the highest amount of rainfall and rainy days, indicating a distinct season with high humidity. Autumn (September–November) brings a gradual decrease in temperature and reduced rainfall, offering comfortable weather for travel.

Iwakuni experiences distinct seasonal changes with noticeable annual temperature fluctuations. The hottest month is traditionally August, when the average temperature reaches 27.0°C, and daytime highs often rise to 29.9°C. Conversely, the coldest month is January, with an average temperature of around 4.9°C, while nighttime lows can drop to 1.8°C. Thus, the annual temperature trend demonstrates a significant contrast between summer warmth and winter coolness.

The summer months in Iwakuni, particularly July and August, are characterised by warm and humid weather. Average daytime temperatures during this period confidently stay above 28°C (for example, in July the average high is 28.4°C, and in August – 29.9°C), while nights remain warm, with temperatures rarely falling below 23-24°C. June brings more moderate warmth with average values around 21.5°C (highs up to 24.5°C) but is already a harbinger of the hot season. The high number of days with precipitation in the summer months, especially in July (19 days), also contributes to the sensation of high humidity.

Winter in Iwakuni is relatively mild and cool, but without severe or prolonged frosts. Average temperatures in December, January, and February range from 4.9°C to 6.4°C. Daytime highs are usually in the range of 7.9°C - 9.3°C, while nighttime lows can approach the freezing point, reaching 1.8°C - 3.6°C. Moderate diurnal temperature variations are observed throughout the year; the difference between daytime highs and nighttime lows is most often between 5°C and 8°C. This ensures a noticeable but not drastic change in temperature sensations throughout the day. Spring and autumn months offer comfortable transition periods with gradually rising (March–May) or falling (September–November) temperatures.

Iwakuni sees pronounced seasonality in precipitation distribution throughout the year. The city experiences a distinct wet season in summer, which is followed by a drier period during the winter months. Overall, the total amount of precipitation is not extremely high, but its frequency varies noticeably between seasons.

The highest amount of rainfall and rainy days occurs from June to September. July is the wettest month: on average, about 10 mm of precipitation falls, and there are approximately 19 rainy days. This indicates frequent but mostly light or moderate precipitation during this period. June, August, and September are also characterised by an increased frequency of rain: between 7 and 8 mm of precipitation falls, and the number of rainy days ranges from 15 to 16, meaning it rains on about half the days of these months.

The driest months in Iwakuni are November, December, and January. Only about 2 mm of precipitation falls in each of these months. The number of rainy days is also minimal at this time, especially in November and December (about 7 days each). Precipitation in these months typically comes in the form of light rain or drizzle. The spring months (March, April, May) and October are transitional, with moderate precipitation of 4 to 5 mm and 9-12 rainy days.

When planning a trip to Iwakuni, it is important to consider the changing seasons so that your wardrobe matches the weather. Comfortable shoes for walking are the first thing to take care of, as the city encourages exploration on foot. Given the temperature fluctuations during the day and between seasons, the principle of layering clothes will be your best ally, allowing you to easily adapt to changing conditions, whether it be a cool morning or a warm afternoon.

In winter (December to February), average temperatures hover around 4-6°C, and minimums can drop to 1-2°C, so warm items are necessary: sweaters, an insulated jacket (preferably waterproof, as even with low rainfall amounts there are up to 10 "wet" days per month), a hat, gloves, and a scarf. In spring (March–May) and autumn (September–November), the weather becomes milder, with temperatures from 9°C to 23°C. During these periods, a light jacket or windbreaker will come in handy. Summer (June–August) in Iwakuni is warm and humid, with average temperatures ranging from 21°C to 27°C, and maximums reaching nearly 30°C. This is also the rainiest season, especially June and July, when the number of days with precipitation can reach 15-19. Therefore, light, breathable clothing, as well as a reliable umbrella or raincoat, are mandatory.

Do not forget important accessories such as sunscreen and a hat, especially during the summer months. A compact umbrella will be useful not only in summer but also in other seasons, as rainy days, albeit with varying precipitation intensity, occur year-round. Overall, preparing for a trip to Iwakuni requires attention to weather details, but the right choice of clothing will ensure you a comfortable and pleasant journey through this interesting Japanese city.