Pokemon GO parent company Niantic decided to postpone the Safari event which was scheduled for August 5 and August 12.Although apart from this two event none other events are been changed or rescheduled.
In order to guarantee the best possible gameplay experience for European Trainers, we have decided to postpone the events in Europe scheduled for August 5 (Copenhagen and Prague) and August 12 (Stockholm and Amsterdam) until a date later in the Fall. No other scheduled events are affected including the event scheduled for Yokohama, Japan on August 14 and the events scheduled for September 16 in France, Spain, and Germany.
We apologize for any inconvenience and hope you understand that our priority is to ensure a great experience for Pokémon GO Trainers in Europe and around the world. Trainers that might have questions regarding the Safari Zone events should visit the help center.
As a special surprise, we understand that some Pokémon that are rarely seen in Europe will be appearing soon in certain European cities for a brief time. Keep your eyes peeled!
Stay tuned for more information, we will update you as soon as we have the new dates.
—The Pokémon GO team
Source: Niantic Labs