Do you mean, "After a storm, people will be in a very good mood" Are you expecting a storm or rain in your area?

You should try asking questions relating to learning English! None of your questions are ever about learning English!

If you are referring to a heavy and violent storm, I think you mean to say "the people affected by the storm counted themselves lucky to be alive and relieved that no one was killed, when the heavy storms that pounded them had finally receded".