At our university, at least when I studied there some 15 years ago, the whole cluster was occupied doing weather predictions each and every night.

No point in staying up waiting for a job, it'd get rescheduled in the early morning at best.

It wasn't the largest cluster around, IIRC 768 quad-core nodes, but I'm sure the meteorological department would find a way to utilize any extra capacity, so still requiring the whole thing all night.

Feels like this might be an invariant in computer science. I once worked on an IBM/360. The majority of the compute was taken up by a single person who did weather simulation.

An IBM/360 has laughably less compute than your phone.

"Computational fluid dynamics is hard" seems like a true bona fide CS invariant.

It might still have produced a better weather prediction than my phone, though /s

ENIAC ran weather as well. It's a kind of numerical simulation that will always be in need of compute cycles. We'll need more of it as we go deeper into climate change.