Spanish (Castilian) · B2 weather

Un día de perros

Literally: "A day of dogs"

A miserable day of terrible weather

Example

No me apetece salir de casa con este día de perros; hace frío y llueve.

I don't feel like leaving the house on this miserable day; it's cold and raining.

Pip says

Even though dogs are cute, a 'día de perros' is anything but! Use it when the weather is so nasty you just want to curl up inside.

What does this phrase mean?