November/December are the months when influenza is in
full swing. Sometimes it can come as early as the last
of September, and hang in there until February or a little
longer.
It is seasonal, and as MrSmith mentioned, along with warm
weather comes the last of the influenza.
That is fine though every year there has always been “some” cases of influenza during the warmer seasons and it should be picking up today. Except for this year. No cases of influenza and it’s not picking up yet. I gave a link earlier. You can see for yourself