When was December 31?

[Talab1234]

Is this correct if I want to ask which day December 31? Was?

Does it make sense?

“When was December 31?”

 

[Barque]

Does it make sense?

“When was December 31?”

The answer you'd get would be "Four days ago" or "Last Saturday" or "Last week".

If you want just the day, you'll need to ask "What day was December 31[, 2022]?"