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 calma antes de la tormenta

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.
Todos estaban callados, pero sabía que era solo la calma antes de la tormenta.
The quiet morning was the calm before the storm of the busy workday.
La tranquila mañana fue la calma antes de la tormenta del ajetreado día de trabajo.