I still count this as a rumor until Apple officially provides the dates, but MacRumors found something they believe confirms the dates.
While we were already confident the WWDC 2019 dates would fall on June 3-7, we confirmed with a source that a large annual event of some kind will be taking place during that week at McEnery. Meanwhile, the second and fourth weeks of June are ruled out due to the already-announced O’Reilly Velocity conference on June 10-13 and the Sensors Expo on June 25-27 at McEnery.
Check It Out: WWDC 2019: June 3-7 in San Jose, California