Sources and methodology

What we show, where it comes from, and the exact rules behind every derived recommendation.

Data sources

Current conditions and forecasts come from WeatherAPI.com, requested by the coordinates of each city in our catalog. Weatheria does not run its own weather model or measuring stations.

This preview currently uses synthetic sample data generated by Weatheria for testing. It is clearly labelled and is not a forecast.

Places come from GeoNames (cities15000, licensed CC BY 4.0): 34,191 cities with roughly 15,000 or more inhabitants, plus capitals. Catalog dump date: 2026-10-28.

Weather alerts, where shown, are passed on from the data provider with their source, validity and area. Missing alerts never mean that there is no hazardous weather.

Freshness

We load current conditions and the forecast together. After 30 minutes we try to refresh them on the next visit; after 55 minutes they are no longer shown at all. If the provider is unavailable, older data is shown only until that limit and then replaced by an “unavailable” notice.

Each page shows when the provider last updated the current conditions, when Weatheria loaded them and until when they are shown. An open page removes expired values on its own.

The best two-hour window

For each local day we compare all two-hour windows made of two consecutive hourly forecasts. These are product preferences for ordinary time outdoors (a walk, a run, a café terrace) – not health or safety standards.

A window is only considered if

• it starts at or after the current time and ends before local midnight;
• both hours are in daylight according to the provider;
• temperature, chance and amount of precipitation and gusts are available for both hours;
• the highest hourly chance of precipitation is at most 40 %;
• total forecast precipitation is at most 0.5 mm;
• gusts stay at or below 45 km/h;
• the temperature stays between 0° and 34°;
• neither hour has these conditions: Thunderstorms possible, Thunderstorm, Thundersnow, Freezing rain, Freezing drizzle, Freezing fog, Ice pellets, Blizzard, Blowing snow, Heavy rain, Heavy showers, Heavy snow, Sleet;
• it does not overlap any weather alert supplied by the provider.

Among the remaining windows we prefer, in this order

1. the lower highest hourly chance of precipitation;
2. less total forecast precipitation;
3. weaker gusts;
4. a temperature closer to the comfortable range of 10° to 26°;
5. the earlier start.

The figure we show is the highest hourly chance within the window. It is not the probability that it will rain at some point during the two hours, and we never multiply hourly chances as if they were independent.

If no window passes all conditions, we say so instead of recommending one. A recommendation is not a guarantee of dry or safe weather.

Daily summary

The short summary is generated by fixed rules from the forecast values shown on the page: the day’s high and low, the first hour with a likely chance of rain or snow (50 % or more, or at least 0.3 mm), gusts from 50 km/h, a UV index from 6, and a change of at least 5 °C in tomorrow’s high. No text is written by hand or by AI for individual cities.

Uncertainty

Forecasts become less reliable further ahead, especially for the timing of showers and thunderstorms. Hourly values describe the most likely development, not a certainty. A chance of rain of 30 % means rain is possible.

“Current conditions” are the provider’s estimate for the city’s coordinates, based on nearby observations and models. They are not readings from a Weatheria station.

Time zones and dates

All times and dates are shown in the local time of each city, using its official time zone including daylight saving time – never the time zone of your device. “Today” therefore means today in that city.

Data is stored in metric units. Switching to °F, mph or inches converts values in your browser and does not load new data.

Weather history

Weatheria keeps an archive of past daily and hourly weather, obtained from the provider’s historical data service, for cities that people use. Forecasts themselves are kept only for a short time, as the provider’s terms require.

Climate pages, when available, use one fixed period and one data source per page and are clearly separated from forecasts.