Primary-source data
Values come from the Japan Meteorological Agency’s published climate normals for major observatories.
A data-first planning reference
Japan is not one climate.
Compare typical monthly conditions across major Japanese cities before you build an itinerary. Clear data, visible differences, no generic “best time” claims.
Climate normals, not a forecast. Data period: 1991–2020.
City comparison
See the gap before you go
Choose a month and up to three cities. The chart shows all-year mean temperature; cards show the selected month.
All-year context
Mean temperature
Why this exists
Useful planning data, with its limits visible.
Comparison, not a verdict
The interface surfaces differences between places. It does not rank destinations or promise a “best” month.
No live-weather claim
Use official forecasts and local guidance close to departure. This prototype intentionally does not offer safety advice.
Editorial layer
Data-led climate guides
Each guide explains one comparison at a time, states the data period, and links back to the source table.
01
How to read Japan’s climate normals
What a 30-year normal is — and what it cannot tell a traveler.
02Tokyo vs Osaka by month
A direct comparison of temperature, rain and sunshine patterns.
03Tokyo vs Sapporo by month
How far north–south differences change through the year.
04Tokyo vs Naha by month
Two distinct climate profiles, shown with the same source data.
05Japan in March: five-city context
What the published normals show across the selected observatories.
06Japan in June: five-city context
A data view of temperature, rain and sunshine differences.
07Japan in September: five-city context
A city-by-city reference for long-term typical conditions.
08Japan in November: five-city context
How the five selected observatories differ late in the year.
09Winter across Japan: north to south
Compare January conditions without treating Japan as a single climate.
10Summer across Japan: north to south
Compare August normals across five major observatories.
11Rainiest month by city
Use precipitation normals to spot regional patterns, not daily likelihood.
12Sunshine hours by city
How to interpret a monthly sunshine total in a trip-planning context.