The auroral activity forecast predicts the expected location of the most active auroral forms that can be expected for the given period. Aurora viewing is also affected by a variety of other factors, such as cloud cover, moonlight, and urban light pollution, so what you see will be strongly affected by your particular location and meteorological luck. The best time to observe aurora is near local midnight, when the most active forms often occur. More precisely, the time to shoot for is an hour or two prior to local geomagnetic midnight, and the forecast maps found here are calculated for that time. If you are a serious aurora watcher, plan to spend the night from about 10 P.M. to 2 A.M. watching for auroral action.
Auroral activity tends to come in waves during an evening, which are called geomagnetic substorms.
The forecasts deal with the average level of activity expected within the prediction period. The sun occasionally produces bursts of unforeseen intensity, so the most spectacular auroral displays can come with little warning.