Weekly climate outlook

The extended range forecast is updated only once a week, usually on Friday.

At the time of publication, it provides an outlook on the tendency of temperature and precipitation to be expected for the week after next. As the forecast week draws nearer, this prediction loses in value. The direct weather forecast, which always considers the latest observations, then provides more accuracy and detail.

The diagram shows the current forecast of the expected tendency of mean temperature and precipitation sum. It is updated once a week.

In the temperature forecast, the height of the columns indicates the probability that the forecast week will on average be cooler than normal (blue), rather normal (green), or warmer than normal (red). In the precipitation forecast, the columns depict the probability that the precipitation sum will be dryer than normal (brown), normal (turquoise), or moister than normal (dark blue).

The three categories are climatologically equiprobable (indicated by the grey horizontal bars). The specific temperature and precipitation values defining these categories for a given season and region are displayed on the diagram. For the region "Nord- und Ostschweizer Mittelland" (Swiss Plateau), the numbers refer to the average of the measurement stations in Basel, Berne and Zurich; for the region "Suisse romande" (Western Switzerland) they refer to the station in Geneva, and for "Sud delle Alpi" (south of the Alps) they refer to Lugano.

Hints for Interpretation

Scientific and technical background

Forecasts stretching beyond a few days into the future are associated with a high degree of uncertainty. It can always happen that unpredictable and chaotic weather events distort the expected mean tendency. At present, our forecasts have a reliability of about 70-80% for temperature, and only 55-60% for precipitation. A forecast strategy based on random guessing would yield 50%. We therefore recommend being cautious when making decisions on the basis of these forecasts.

Since the forecast is updated only once a week, it loses in value as the predicted week draws nearer. The direct weather forecast  then provides more accuracy and detail.

Yes. MeteoSwiss calculates the tendency of weekly temperature means and precipitation sums for up to four weeks into the future, and for any region in the world. Of course, prediction reliability drops quickly as the prediction range is increased. However, in some regions of the Earth, especially in the Tropics, even forecasts of four weeks into the future can still have a reliability of about 70%.

For further information regarding our extended range forecast products you may contact us here.

Please also note that MeteoSwiss regularly issues a seasonal climate outlook on the internet.