About this service

This site shows statistical tendencies from past observations and reanalysis. It also shows year-by-year temperature and humidity (including a recent 5-year average) alongside clear/cloudy/rain by time of day. You specify a place and calendar date before aggregation. It is not a substitute for same-day forecasts or warnings.

Notes

Places and weather data are limited to Japan for now. Maps and reverse geocoding may show nearby regions, but aggregation is only for coordinates inside Japan.
Past distributions may not match future experience (e.g. climate change).
Categories like “clear” and “cloudy” follow fixed definitions tied to the dataset and are shown on screen.
“Year-fate nine-star trip directions” is a simplified cultural feature. Solar-term and nine-star math uses lunar-javascript (6tail / MIT). Results can differ by school.
Some data uses the Historical Weather API from Open-Meteo. Follow Open-Meteo’s terms for usage and commercial use; we will keep site terms updated.

Place search uses OpenStreetMap Nominatim and Open-Meteo geocoding. Map pin labels may use Nominatim reverse geocoding. We follow Nominatim usage policy (User-Agent, rate limits).

Planned extensions

Cross-checks with JMA Amedas and location-specific thresholds.
Compare multiple places, list views, etc.

Operation

We aim for a free site without login. Contact info will be added when ready.