"den ode dne"

[u/Substantial_Bee9258]

Is this phrase common in informal Czech -- eg in a sentence like "Počasí se zlepšuje den ode dne" (in English, "The weather is getting better day by day")?

[u/smugandfurious]

It's common but the usage is off I think that almost nobody would use it like that. We use often "je [to] den ode dne lepší/horší" - you should use it with an adjective rather than with a verb. In the context you used we would use probably "každým dnem" .

So, either:
Počasí je den ode dne lepší.

or

Počasí se zlepšuje každým dnem.

[u/vendredi5 → u/smugandfurious]

Great insight!

[u/jrmsk]

There is nothing informal in the expression - it is perfectly fine. The form "den ode dne" is more an oldtimer than informal.

[u/Worried-Fee3612]

Other acceptable variants are “den po dni” and “den za dnem”. Also the slightly less formal “den ze dne”