"Είναι μία φυσιολογική ημέρα."

Translation: It is a normal day.

[Lng52-._]

Can you also use "κανονικός" for normal?

[Dimitra956826]

Yes, you can. ^.^

[J.C.M.H.]

I wonder how physiological would be in Modern Greek.

[PauloMuffato]

Φυσιολογικός.

[RaleighStarbuck]

I was about to ask a similar question to what Lng52 asked, but with "συνήθης." Υπάρχουν "φυσιολογικός" "κανονικός" και "συνήθης"... ποια είναι η διαφορά μεταξύ όλων αυτών των λέξεων;

[D_..]

Συνήθης is just 'usual', it might not be normal! ;)
Wordreference gives συνήθης as a translation of normal, and there is overlap indeed -see the example. It's not wrong, but I would keep the distinction between κανονικός=normal and usual=συνήθης/συνηθισμένος. (Συνήθης is more old-fashioned and formal than συνηθισμένος but there's no need to avoid using it, it's fine.)
Φυσιολογικός is also normal -or physiological! :)

[Lobitone]

Then everything changed when the Fire Nation attacked