Adding a place (search, server list, personal list)
Search a town by name (GeoNames via Open-Meteo), check its region and country, then add it. On a public site, only the admin can add to the shared list; anyone can keep a personal list in their own browser.
Data and trust
Shared list (server): the place is collected like the others (forecast, air, warnings, advisories within a minute; climate normals, projections and river levels over the next days).
Personal list (this browser): stored in localStorage only. It shows the current conditions and 7-day forecast, the El Nino sensitivity and the country advisories, not the long-term matrix.
Always check the region shown in the search results: many towns share a name (there are three Gorokhovets in Russia). The default places were checked against OpenStreetMap as well.