Isahaya Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Isahaya.
Climate overview of Isahaya
Isahaya, Nagasaki, Japan, sees big temperature differences between seasons, with August peaking at 31°C (88°F) and January dropping to 11°C (52°F).
Rainfall is high, totalling around 2173 mm (86 in) per year. June is the wettest month and January the driest. The city also experiences a distinct rainy season from May to September, with very warm summers and cold winters. The most sunshine falls in August, with an average of 7.0 hours of daily sunshine.
Isahaya Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Isahaya - and find the best time to visit.
Monthly Temperature in Isahaya
Visitors to Isahaya can expect significant temperature changes throughout the year. Average maximum daytime temperatures range from a very warm 31°C (88°F) in August, the warmest time of the year, to a chilly 11°C (52°F) during cooler months like January.
At night, you can expect temperatures ranging from 26°C (79°F) in August to around 6°C (43°F) during January.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Isahaya
Isahaya is known for its substantial rainfall, with annual precipitation reaching 2173 mm (86 in). Significant seasonal changes in precipitation occur throughout the year. In the wettest month, June it receives heavy rainfall, averaging 443 mm (17 in) of precipitation, recorded across 19 rainy days. In contrast, the driest month January brings less rainfall, with 80 mm (3.1 in) over 20 rainy days. For more details, please visit our Isahaya 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 Isahaya
Seasonal changes in sunshine hours are quite dramatic in Isahaya. While August receives considerable daily sunshine with up to 7.0 hours, January marks the darkest time of the year, where sunshine is scarce with only 3.5 hours of sunlight per day.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Water Temperature in Isahaya
The mean water temperature over the year ranges from 14°C (57°F) in February to 27°C (81°F) in August.
Water temperature over the year
Humidity in Isahaya by Month
The relative humidity is high throughout the year in Isahaya.
The city experiences its highest humidity in June, reaching 80%. In February, the humidity drops to its lowest level at 65%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Wind Speed in Isahaya
The average wind speed over the year ranges from 1 m/s (2 knots) to 2 m/s (4 knots). It is lower in September and October and higher in January, February, March, April, May, June, July, August, November and December. What does this mean?
The mean monthly wind speed over the year (meters per second)
Best Time to Visit Isahaya
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: October
- Warmest weather: July and August
- Most sunshine: August
- Fewest rainy days: May, October and November
- Best for swimming: June, July, August, September, October and November.
- Wettest months: May, June, July, August and September, when rainfall is highest.
- Seasonal pattern: A distinct rainy season from May to September, with very warm summers and cold winters
Frequently asked questions about the climate in Isahaya
What is the best time to visit Isahaya?
October typically offers the most optimal weather in Isahaya. In contrast, February, June, July and August tend to have less optimal conditions. Isahaya has a distinct rainy season from May to September, with very warm summers and cold winters.
What temperatures can I expect in Isahaya?
Daytime highs range from 11°C (52°F) in January to 31°C (88°F) in August. Nighttime lows range from 6°C (43°F) to 26°C (79°F). Temperatures vary considerably through the year.
How much rain does Isahaya get?
Annual rainfall is around 2173 mm (86 in). June is the wettest month with 443 mm (17 in), while January is the driest with 80 mm (3.1 in).
How sunny is Isahaya?
Isahaya receives around 1,876 hours of sunshine per year. August is the sunniest month with 209 hours, while January is the cloudiest with just 104 hours.
Isahaya 3-Day Forecast
Isahaya on the map
Isahaya is highlighted - select any city to see its climate.
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