the calm before the storm

US /ðə kɑːm bɪˈfɔːr ðə stɔːrm/
UK /ðə kɑːm bɪˈfɔːr ðə stɔːrm/
"the calm before the storm" picture
1.

la quiete prima della tempesta

a period of unusual quiet or inactivity before a period of great activity, excitement, or trouble

:
Everyone was quiet, but I knew it was just the calm before the storm.
Tutti erano tranquilli, ma sapevo che era solo la quiete prima della tempesta.
The quiet morning was the calm before the storm of the busy workday.
La tranquilla mattinata era la quiete prima della tempesta della giornata lavorativa intensa.