Product behaviour

Harmattan behaves like a product rather than a table of weather values.

Greeting

The interface derives a greeting from local time, moving through good night, good morning, good afternoon, and good evening according to the hour.

Temperature units

Users can switch between Celsius and Fahrenheit. The display value is converted locally rather than requiring a second weather request.

Theme

The interface supports dark and light modes and persists the selected theme locally.

Contextual weather lines

The mood copy is not generated by a live AI model. It comes from an internal bank selected according to weather category and can be extended by contextual pools for heat, humidity, wind, and night.

Dynamic condition presentation

The visual treatment responds to weather category and day/night state.

City changes

When the active city changes, Harmattan updates state, persists the city, requests fresh weather, guards against stale responses, and rerenders the interface.

Search boundary

City search is limited to the curated Nigerian dataset. It is not worldwide geocoding.