The species may occasionally occur there in very high numbers.

Although usually black, red, yellow and brown individuals do occasionally occur.

Rocket fire occasionally occurs in the early morning when children head to school.

Usually a single young is born, but twins occur occasionally.

Currently, such meetings occasionally occur, but they are not required.

There, in the central part where most species come from, frost occasionally occurs.

Species that have not been observed in a region may still occasionally occur there.

To some degree, it may occur occasionally to otherwise healthy people.

It occasionally occurs in people with an apparently normal general condition.

Summer thunder storms occasionally occur, particularly in the later part of the season.