The Seasonal outlook basin overview layer shows the maximum area-averaged probability of unusually high (> 80^th percentile, blue) or low (<20^th percentile, orange) weekly river flow occurring during the four 4-month forecast horizon for 305 major world river basins, using colour-coded cetagories:

• Dark blue: > 90% probability of high flows
• Medium blue: 75-90% probability of high flows
• Light blue: 50-75% probability of high flows
• Light orange: 50-75% probability of low flows
• Medium blue: 75-90% probability of low flows
• Dark blue: > 90% probability of low flows