A rainfall forecast issued in September 2005 suggests that rainfall in December 2005 will be lower than normal in Northwest Africa and higher than normal in the Sahel and in East Africa. Probability seasonal forecasts are computed by linking computer models that simulate the motions and energy transfers in the atmosphere and ocean and then running tens of cases to encompass the range of uncertainties in observations and in the numerical models. The probabilities are then computed from the ensemble of individual forecasts.

The question then remains: how much higher or lower than normal. The anomaly forecast issued in September 2005 suggests that rainfall will be about 50-60% below normal during December 2005 in Northwest Africa (Algeria, Tunisia) and Southwest Asia (Pakistan, Afghanistan), and will be up to 300% higher than normal in East Africa (Ethiopia, Djibouti, Somalia) and the southwest Arabian Peninsula (Yemen).

A seasonal forecast issued in January 2006 suggests that temperatures in June 2006 will be higher than normal in Northeast Africa and in southern Yemen but lower than normal in the Persian Gulf, along the Indo-Pakistan border and in parts of West and Northwest Africa.

Again, how much warmer or cooler could it be? The forecast issued in January 2006 suggests that temperatures may be about 1°C lower than normal in June 2006 in Morocco, the Persian Gulf and along the Indo-Pakistan border and about 1°C higher than normal in Northeast Africa and the southern Arabian Peninsula.

In 2020, the seasonal predictions were further improved by making use of six models: CFSv2, ECMWF and Copernicus (CMCC, DWD, MeteoFrance, UKMO). The more models, the better the overall forecast. Consequently, the seasonal predictions provided by the World Climate Service are one of the most sophisticated in the world.

In addition to the six-month seasonal predictions, WCS provides sub-seasonal predictions of temperature and precipitation anomalies for up to six weeks in advance derived from multiple models. Subseasonal predictions are useful for field operations, especially during locust control campaigns because they can offer guidance in the optimal use of resources.