The 2021 WorldCon, to be held in Washington, D.C., is holding a public debate on moving the date of the convention to December.
WorldCon is traditionally held in the late summer or early autumn, with August and September emerging as the most common dates for the convention. However, DisCon III (as the 2021 event is named) is considering a move from 25-29 August to 15-19 December for several reasons.
The most obvious reason is the ongoing COVID-19 pandemic. With vaccination programmes starting next week in the UK and across the world in the next few months, it appears that many people will be vaccinated and able travel next year. However, August may make it too tight for some to make it, particularly in the United States where the majority of over 320 million people need to vaccinated, clearly a colossal undertaking. It appears that WorldCon does not have a huge amount of faith that enough people will be vaccinated to make the convention financially viable; thus, if people want a WorldCon in August, it will have to be an online-only, virtual event, like last year's New Zealand WorldCon (I suspect the convention centre and hotels have been pressing for a final commitment).
Moving the date to December gives a lot more people more time to get vaccinated. There are also some auxiliary benefits, such as giving people more time to get up to speed on 2020's book, TV, film and video game releases for the Hugo Awards.
The move to December does have several possible problems. The first is that the vote for the 2023 WorldCon Bid is due to be held at WorldCon. Moving that vote from August to December gives the host city that wins (which will almost certainly be Memphis, Tennessee; Chengdu, China is not considered a realistic prospect at this time, but of course that is not 100% confirmed until the bid vote) four months less of prep and organisation time. That problem could be overcome with a separate, online bid vote in August. There are also other SFF conventions taking place, if not on that weekend, then certainly nearby. SMOFCon is a couple of weeks earlier, for example.
A date just one week before Christmas does create a lot of other problems, of course, and there will be issues with people having already booked their dates off for August and not able to change them at this stage. However, I can see the appeal of trying to manage an in-person convention if at all possible.
DisCon III will be assessing the arguments for and against the move, and considering the survey results before making a final call.