Specifically, it's 2020 in the UTC+14 zone occupied by Kiribati and Kiritimati, the latter being somewhat to the east of Hawai'i (UTC-10). So begins the 24-hour period where some part of the world goes from 2019 to 2020 every hour (or, in the case of India, Nepal, Afghanistan, Newfoundland, and a couple of other places, at the half- or quarter-hour).
So welcome to the '20s, Kiribati.