"Calm days" refers to peaceful and quiet periods of time where there is a lack of stress, excitement, or chaos. It describes a state of tranquility and an absence of disturbances or intense emotions.
Sentences with «calm days»
Best viewing times are on calm days with little or no wind. (cbhistory.org)
The smooth sand might seem an inviting place to build, and in calm days the house would seem secure. (religion-online.org)
On the contrary: flooding even occurs on sunny, relatively calm days. (sciencedaily.com)