The media gathering at the company's intimate Town Hall auditorium in Silicon Valley will also give Apple a chance to restate its case for fighting a US government demand that it break into an attacker's iPhone.
Apple is widely expected to release a small-screen iPhone to encourage replacement of the 5S and 5C models, which have four-inch displays. The new device is to be called the iPhone SE or 5SE, reports said.
This would help Apple in a traditionally slow season before the likely upgrades to the large-screen iPhone 6 family later this year.
But in keeping with its practice, Apple has been tight-lipped about what it will reveal. A message on copies of the invitations posted online simply states "Let us loop you in," prompting some to
speculate that new bands for the Apple Watch would be among the announcements.
A four-inch screen iPhone which boasts improvements under the hood could help spur replacements. Such an iPhone would be "an incremental positive" for Apple, ensuring that lovers of the company's smaller smartphones don't switch to rival devices powered by Android software, RBC Capital Markets said in a note to investors.