the calm before the storm
US /ðə kɑːm bɪˈfɔːr ðə stɔːrm/
UK /ðə kɑːm bɪˈfɔːr ðə stɔːrm/
1.
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.
•
The quiet morning was the calm before the storm of the busy workday.