Siri varies the timing of Apple's developer event "WWDC 2016"
The biggest event Apple hosts for developersWWDC"Is held in June of the same year, but it turned out that Personal Assistant Siri had been broken by the time of WWDC 2016 held this year.
Apple - Press Info - Apple's Worldwide Developers Conference Kicks Off June 13 in San Francisco
Siri announces WWDC 2016 will be held June 13th through June 17th in San Francisco [Update] | 9to 5Mac
According to 9to5Mac, when asking "When is WWDC?" Towards Siri, Siri said "The Worldwide Developers Conference (WWDC) will be held June 13 throhgh June 17 in San Francisco. I can not wait! (WWDC I will be holding in San Francisco from June 13 to June 17. I can not wait! " Incidentally, at this point HP has not announced on WWDC 2016 from Apple including press release as well. So, Siri seems to have been releasing WWDC 2016 's holding date and venue at flying.
Later on April 18, 2016 (local time), a release was officially announced from Apple that WWDC 2016 will be held in San Francisco from June 13, 2016 to June 17.
With WWDC 2016, which was announced at the flying by Siri, "iOS 10" and a thin MacBook appeared, it is expected that renaming to "MacOS (or macOS)" for desktop OS will be announced .