WWDC attendees greeted with jackets featuring Apple Watch San Francisco font, Swift code

The windbreaker-style swag jacket lacks an Apple logo, instead simply stating "WWDC 2015" on the front with a large "15" on the back, nearly identical to the jackets Apple gave attendees last year.

There are a couple differences, principally the use of the San Francisco font that alludes to the company's new Apple Watch, which promises to get prime developer attention at the week-long conference.

It's likely that Apple's new iOS 9 and the next 10.11 version of OS X will also adopt the new font as their system default, providing a freshened appearance that harmonizes the overall appearance of the company's platforms.

While similar in style to the fog-resistant polyester-spandex jackets from WWDC 2014, this year's jackets also sport invisible zippers for their front pockets (as opposed to the open pockets last year).

While the fleece-lined, albeit lightweight, jacket might seem out of season in California in the month of June, San Francisco is infamous for its June Gloom, where days may be sunny but as soon as the sun goes down the fog rolls in and temperatures can plunge below their lowest point from the calendar's winter.

In another coy reference to its technology, Apple has outfitted its jackets with a garment tag that designates its size and comments that it was "Made in the USA" using code written in Swift, the new programing language introduced at last year's event.

The tag reads: 'let jacketSize = "Medium"' and "// Made in the USA," following Swift's conventions for assigning variables and adding code comments, in numbered lines and color coded text familiar to Apple's Xcode developers.

A few attendees are already lined up outside the Moscone West convention center, ready to sleep on the sidewalk tonight in order to be among the first to grab seats. Registration staff noted that Keynote attendees should be able to get a good seat if they're "in line by 5 am," but added that this year Apple will make sure everyone in attendance will get a seat.

Those not at the conference will be able to watch the WWDC Keynote via a live feed starting at 10 AM PST, via the web or Apple TV.