Iwanai Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Iwanai.
Climate overview of Iwanai
Temperatures in Iwanai, Hokkaido, Japan, vary greatly throughout the year. August is the hottest month at 25°C (77°F), while January is the coldest at -1°C (30°F).
With around 1416 mm (56 in) of annual rain/snowfall, Iwanai has a notably wet climate. However, this rain/snowfall is not evenly distributed, the city has warm summers and very cold winters. The wettest month is August. Sunshine peaks in May, when the city sees around 6.6 hours of sunshine per day.
Iwanai Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Iwanai - and find the best time to visit.
Monthly Temperature in Iwanai
The climate in Iwanai is known for significant temperature differences throughout the year, making the weather dynamic. Average daytime temperatures reach a comfortable 25°C (77°F) in August. In January, the coolest month of the year, temperatures drop to a very cold -1°C (30°F).
At night, temperatures range from around 18°C (64°F) in August to -7°C (19°F) in January.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Iwanai
Iwanai has a notably wet climate with abundant precipitation, recording 1416 mm (56 in) of rain/snowfall per year. Iwanai can be quite wet during August, receiving approximately 171 mm (6.7 in) of precipitation over 18 rainy days.
In contrast, during the driest month (April), you will experience much drier conditions, with 78 mm (3.1 in) of precipitation spread across 18 rainy days. For more details, please visit our Iwanai Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Iwanai
Iwanai can be enjoyed more throughout the sunniest month of May under a blue sky, with approximately 6.6 hours of sunshine daily. In contrast, the city experiences much darker days in December, with only 2.9 hours of sunlight per day.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Humidity in Iwanai by Month
The relative humidity is high throughout the year in Iwanai.
The city experiences its highest humidity in July, reaching 76%. In April, the humidity drops to its lowest level at 62%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Iwanai
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: June, July, August and September
- Warmest weather: July and August
- Most sunshine: May
- Seasonal pattern: Warm summers and very cold winters
- Coldest conditions: January, with freezing nights around -7°C (19°F).
Frequently asked questions about the climate in Iwanai
What is the best time to visit Iwanai?
June, July, August and September typically offer the most optimal weather in Iwanai. In contrast, January, February, March, April, November and December tend to have less optimal conditions. Iwanai has warm summers and very cold winters.
What temperatures can I expect in Iwanai?
Daytime highs range from -1°C (30°F) in January to 25°C (77°F) in August. Nighttime lows range from -7°C (19°F) to 18°C (64°F). Temperatures vary considerably through the year.
How much rain does Iwanai get?
Annual rainfall is around 1416 mm (56 in). August is the wettest month with 171 mm (6.7 in), while April is the driest with 78 mm (3.1 in).
How sunny is Iwanai?
Iwanai receives around 1,749 hours of sunshine per year. May is the sunniest month with 199 hours, while December is the cloudiest with just 87 hours.
Iwanai 3-Day Forecast
Iwanai on the map
Iwanai is highlighted - select any city to see its climate.
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