Looking on the internet deeply has found these results:

appropriate for the occasion is the most popular phrase on the web.

appropriate to the occasion 14,750,000 results on the web	appropriate for the occasion 14,930,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
I think this is a more appropriate occasion. These issues are raised at all appropriate occasions and at the highest political level. These positions are regularly being communicated to China at appropriate occasions. I trust you to find the appropriate occasion. I shall compose something appropriate for the occasion. That would certainly be appropriate to the occasion. Second, my diction is appropriate for the occasion. The Commission raises all these issues with the Turkish authorities on all appropriate occasions.	I think this is a more appropriate occasion. I shall compose something appropriate for the occasion. That would certainly be appropriate to the occasion. The Commission raises all these issues with the Turkish authorities on all appropriate occasions. These positions are regularly being communicated to China at appropriate occasions. These issues are raised at all appropriate occasions and at the highest political level. I guess Stella McCartney was the appropriate choice for the occasion. Second, my diction is appropriate for the occasion.

appropriate to the occasion

14,750,000 results on the web

appropriate for the occasion

14,930,000 results on the web

More popular!

I think this is a more appropriate occasion.
These issues are raised at all appropriate occasions and at the highest political level.
These positions are regularly being communicated to China at appropriate occasions.
I trust you to find the appropriate occasion.
I shall compose something appropriate for the occasion.
That would certainly be appropriate to the occasion.
Second, my diction is appropriate for the occasion.
The Commission raises all these issues with the Turkish authorities on all appropriate occasions.

I think this is a more appropriate occasion.
I shall compose something appropriate for the occasion.
That would certainly be appropriate to the occasion.
The Commission raises all these issues with the Turkish authorities on all appropriate occasions.
These positions are regularly being communicated to China at appropriate occasions.
These issues are raised at all appropriate occasions and at the highest political level.
I guess Stella McCartney was the appropriate choice for the occasion.
Second, my diction is appropriate for the occasion.