From what you've written, you want it to be potentially survivable by everyone. Those that live make it out. Those that die, repeat until they live.
From this, you don't want anything that's utterly impossible for some people to survive. Say, Yellowstone erupting. A great many people would have no chance to survive, regardless of what they do.
What also adds to this is the fact that very few disasters would even affect the world within such a short time period. An asteroid impact in the middle of the Pacific would take hours for the waves to reach shores, and (Speculating here) potentially days for earthquakes to happen - or even finish.
Pretty much any natural disaster isn't going to work here. You need something artificial.
Global nuclear war is definitely on the table. It has a very clear start - It'd happen probably within a matter of minutes. People would have warning before they died - Alarms, etc. Normally, I would say news reports, but with people surviving not coming back, these would quickly vanish after the first few cycles. There's also more sci-fi things that could tie into the time loop. Some crazy superweapon has it as a side effect.
Additionally, this is a situation where fewer people can actually be helpful. You'll want to evacuate cities. As each cycle goes, you'll have fewer cars, fewer people, etc getting in the way.
This would require a slight change to how things function. It would have to reset to just after all of the launch codes were implemented.
With it being such a short period, you also have some neat things that would otherwise be problematic. If you're in a passenger plane, and the pilot manages to land you safely somewhere, you just have to live the day. The whole plane is likely to live or die as one. You don't have to worry as much about the pilot living (And not coming back) while the passengers don't, at least not as much.
There's also the potential for people to realize what is going on. They die a time or two, and notice the people who live don't come back. They make a few assumptions, and decide to ensure they die each day so that they can go back and help others. They can take their knowledge of concrete events to help people. That is, something along the lines of the orbital laser that blows up their city leaves these four buildings in good condition, and this subway station is a good hiding space.